Backpacking Jargon

Backpacker in Grand Teton National Park thinking WTH is a CYTC?

Backpacking: Camping and hiking while carrying almost everything needed in a backpack
Jargon: Expressions used by a group that are hard for others to understand
Backpacking Jargon: Simple explanations of jargon used by backpackers in America

“When I use a word,” Humpty Dumpty said
in rather a scornful tone,
“it means just what I choose it to mean —
neither more nor less.”
Lewis Carroll, Through the Looking Glass

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 F    G    H    I    J  

 K    L    M    N    O  

 P    Q    R    S    T  

 U    V    W    X    Y  

 Z   0-9

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A

A-frame: Also pup tent, tent with flat fabric panels and two straight poles the same length at each end, forming two legs of an upright triangle

ABC: Airway, Breathing, and Circulation, old memory aid for highest-priority first aid problems, now ABCDE

ABC watch: Wristwatch that displays Altitude, Barometric pressure, and Compass headings

ABCDE: Airway, Breathing, Circulation, Decision to maintain spine control, Expose life threatening injuries, memory aid for highest-priority first aid problems

ac: Acre, about 0.4 ha or an American football field without end zones

Access trail: Also feeder trail, connects main trail to a trailhead or another trail

Acclimatization: Ascending slowly while adapting to high altitude, to prevent acute mountain sickness or worse

Achilles tendon: Connects calf muscles to heel

ADT: American Discovery Trail, 6,800 mile (10,900 km) route from the Atlantic Ocean in Delaware to the Pacific Ocean in California

ADZPCTKO: Annual Day Zero Pacific Crest Trail Kick Off event, no longer held

AFAIK: As Far As I Know

Al: Aluminum or aluminium

Alcohol stove: Stove that burns alcohol

ALDHA: Also ALDHA-East, Appalachian Long Distance Hikers Association

ALDHA-West: American Long Distance Hiking Association West

Alpine start: Begin hiking well before sunrise to avoid rockfall and other hazards as the day warms

Alpine zone: Above treeline in high-elevation areas

Alternate: Different trail connected to the main trail at each end

Altimeter: Device that measures altitude using air pressure

Altitoots: Farting because of high altitude

AMC: Appalachian Mountain Club

AMS: Acute Mountain Sickness, headaches, vomiting, and more caused by altitudes above 8,000 feet (about 2,400 m)

Anemometer: Device that measures wind speed

Anker: Brand of battery packs popular with thru-hikers

AQI: Air Quality Index, higher numbers are worse

Aquamira: Brand of liquid two-part chemical water treatment

Arc’x: Arc’teryx, company that makes backpacking gear

As the crow flies: Most direct path between two points, versus by trail or road

AT: Appalachian Trail, 2,200-mile (3,500 km) trail through the Appalachian Mountains from Georgia to Maine

ATA: Appalachian Trail Alliance

ATC: Appalachian Trail Conservancy, formerly Appalachian Trail Conference

Atmospheric river: Also pineapple express, narrow band of airborne moisture that can cause intense rain and snow storms along the west coast of North America

Avalanche: Sudden, dangerous, and rapid downward flow of snow on a slope

Avalanche beacon: Also avy beacon, small radio transmitter and receiver worn while traveling through avalanche areas to aid rescue

AYCE: All You Can Eat, feature of restaurants popular with thru-hikers

AYH: American Youth Hostels

AZT: Arizona Trail, 800-mile (1,300 km) trail across Arizona from Mexico to Utah

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B

Backboard: long, narrow, rigid board with straps used to carry an injured person

Backcountry: Area with no maintained roads and few buildings or residents

Bacon stretcher: Mythical device designed to stretch bacon

Bald: Low forested mountain without trees on top

Barefoot shoes: Shoes with very thin soles, often with individual toes

Barometer: Device that measures air pressure

Base layer: Innermost clothing, usually intended to quickly move moisture away from the skin

Baxter: Baxter State Park in Maine, north end of the Appalachian Trail

BBQ: Barbecue

Beanie: Also toque, warm knit cap

Bear bag: Bag used to hang food out of reach of bears

Bear box: Bear-resistant locker for food storage

Bear burrito: Sleeping bag or hammock with a smelly backpacker inside, usually cowboy camping

Bear cable: Cable permanently installed high between trees or poles for hanging bear bags

Bear can: Bear-resistant food container carried by backpackers

Bear fortune cookie: Tent

Bear piñata: Suspended bear bag low enough for bears to reach

Bear spray: Canned pepper spray used to discourage actively charging bears

Bearmuda triangle: Keep stored food, kitchen, and sleep area at least 100 yards (meters) apart

Beaver fever: Giardia infection

BeiDou: Chinese satellite navigation system like GPS

Bench: Long flat area on the side of a hill

Bergschrund: Also schrund, crevasse formed at the top of a glacier, often quite deep

Berm: Long dirt pile along on the outer edge of a trail

Beta: Recent first-hand information

Bidet: Device used to squirt water and clean up after pooping, instead of using toilet paper

Big three: Backpack, sleep system (like a sleeping bag and pad), and shelter (like a tent)

Bite valve: Mouth-operated valve on the end of a tube leading to a hydration bladder

Bivouac: Sleep outside without a shelter in bad weather

Bivy sack: Separate lightweight cover around a sleep system

Black blazer: Someone who obscures or blacks-out blazes to prevent other hikers from finding a trail

Black ice: Thin, slippery, almost invisible coating of clear ice on rocks, sidewalks, and roads

Blackflies: Small biting flies found in large swarms in the eastern U.S.

Blaze: Carved or painted mark on a tree or rock, showing the route

Blaze orange: Bright color worn during hunting season to reduce accidental shootings

Bliss index: Scale of 1 to 10 measuring backpacker happiness, where 10 is happiest

BLM: Bureau of Land Management, U.S. Government agency managing over 386,000 square miles (over 1,000,000 km²) for multiple uses

Blow out: Serious hiking shoe failure requiring repair or replacement

Blowdown: Trees fallen across a trail or wide area after high winds

Blue bagging: Carrying poop out of the backcountry in blue WAG bags

Blue blaze: Spur trails off the Appalachian Trail marked by blue blazes

Blue-blazer: Backpacker who uses blue-blazed Appalachian Trail sections instead of white-blazed

Bluebird day: Day with blue, cloudless skies

BLUF: Bottom Line Up Front, conclusion at the top with details below

Bluff: Short cliff

BMT: Benton MacKaye Trail, 288-mile (463 km) trail from Georgia to North Carolina

Boardwalk: Trail segment covered with planks to protect sensitive areas

Bog bridge: Also puncheon, narrow walkway to protect wetlands

Bomb cyclone: Quickly developing severe storm

Bomber: Unusually strong or durable gear; also a good rock climbing hold

Bombogenesis: Fast, sustained pressure drop in a developing storm, creating a bomb cyclone

Bonk: Suddenly run out of personal energy due to lack of blood sugar

Bonus miles: Extra distance backpacked on a thru-hike without forward progress, like hiking to town and back for supplies

Book time: Guidebook time to complete a trail

Bounce box: Also drift box or flyer, package of thru-hiker supplies not needed soon, so shipped ahead

BPL: Backpacking Light, online publication with active community forums

BPW: Base Pack Weight, also baseweight, total weight of backpack with everything inside except consumables like food, water, and fuel

Brain: Backpack lid with a zippered pocket

Break trail: Flatten a path through fresh snow that others can follow easier

Breathable: Fabric ability to pass water vapor

Brick-and-mortar: Retail stores you can buy stuff from, versus online shopping

Bridge hammock: Hammock with bars on both ends creating a flatter sleeping surface

Brown blazing: Off trail detour to poop

BRP: Blue Ridge Parkway, National Park unit in North Carolina and Virginia

BSA: Boy Scouts of America

BSI: Big Sky International, company that makes backpacking gear

BSL: Big SEKI Loop, 155-mile (249 km) route through Sequoia and Kings Canyon National Parks, California

BTDT: Been There, Done That, direct experience with the subject

Bubble: Also pack or herd, main group of thru-hikers moving along a trail, typically spread out across several days

Bucket list: List of adventures to complete before “kicking the bucket” (dying)

Buffer zone: Protected areas adjacent to the Appalachian Trail

Bushwhack: Difficult hiking through dense bushes and branches

Bypass: Skip a trail segment, town, or trailside attraction

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C

c: Cup, about 240 ml, exactly 8 ounces volume

C: Celsius, metric measure of temperature, 0 C is 32 F, 86 F is 30 C

Cache: pronounced cash, food and supplies hidden for later pick up

Cairn: Also duck, tall rock pile that might indicate the trail path

Calorie loading: Eating lots of high calorie food during a town stop

CalTopo: Website and app for mapping and navigating backcountry adventures

Camel up: Also tank up, drink a lot of water at a water source

Camp clean: Clean enough but not that clean

Canadian clipper: Also Saskatchewan screamer, Alberta clipper, storm system from Alberta that rapidly crosses the continent

Canister stove: Backpacking stove that burns butane-propane fuel from pressurized metal cans

Canopy: Top layer of a forest

Canyoneering: Also canyoning, traveling the length of rugged canyon bottoms by rock climbing and swimming

Can’t see the forest for the trees: Foreground features hide important background features; also a detail-oriented person missing the bigger picture

Carbs: Carbohydrates, major part of most backpacker diets, including sugary foods, pasta, couscous, and tortillas

Caretaker: Also maintainer, person who maintains a permanent shelter or campsite

Cat hole: Small hole dug to dispose of poop

Catenary curve: Natural curve that rope or fabric makes while suspended between two points

CBS: Cold Butt Syndrome, when hammock campers sleep without enough insulation underneath them

CCF: Closed Cell Foam, dense plastic foam used for sleeping pads and backpack padding

CDT: Continental Divide Trail, 3,100-mile (5,000 km) trail through the Rocky Mountains from Mexico to Canada

CFM: Cubic Feet per Minute, about 7.5 gallons per minute or 28 liters per minute

CFS: Cubic Feet per Second, about 7.5 gallons per second or 28 liters per second

Chafing: Pain and redness where skin rubs together or gear rubs skin, aggravated by sweat and dirt

Chinook winds: Warm southwest winds on the coast of Oregon and Washington; also warm west winds on the eastern slope of western North American mountain ranges

Chrome dome: Discontinued lightweight reflective umbrella, the name now describes similar umbrellas

Christmas toes: Tingling and numbness in thru-hiker toes that lasts through December 25

ci: Cubic inch, about 16.4 ml; 1,000 ci is about 16 liters

Cirque: Also corrie or cwm, steep-sided mountain valley with closed upper end

Class 1 climb: Trail hiking

Class 2 climb: Low-risk scrambling, sometimes using hands

Class 3 climb: Higher-risk scrambling, handholds needed, rope sometimes used to stop falls

Class 4 climb: Simple rock climbing, rope often used to stop falls, unroped falls may be fatal

Class 5 climb: Technical rock climbing, rope usually used to stop falls, unroped falls typically fatal

Class I rapid: Short, fast river section with small waves and no obstacles

Class II rapid: Short, fast river section with easily avoided obstacles

Class III rapid: Short, fast river section with irregular waves, tight channels, and multiple maneuvers required

Class IV rapid: Short, fast river section with unavoidable large waves, critical maneuvers required, and stopping for inspection usually required

Class V rapid: Long dangerous river section, stopping for inspection difficult, and difficult rescues

Cliffed out: Off-trail route that becomes too steep to proceed safely

Clo: Clothing insulation measurement, about 1.55 togs or R 0.88

ClO2: Also ClO2, chlorine dioxide, chemical water disinfectant

cm: Centimeter, about 0.4 inches

CO: Carbon monoxide, colorless odorless poisonous gas, formed by flames or combustion without enough oxygen

Cobbknocker: Also webwalker, web face, or web master, first person on a trail in the morning, who clears spider webs

Cobble: Rounded rocks 2.5 to 10 inches (65-256 mm) across

Cobblestone: Path built from cobbles

Col: Also gap, notch, or sag, low point on a ridge

Cold soak: Prepare food by soaking it in water without cooking

Comfort hiker: Backpacker carrying much more weight in the pursuit of camping comfort

Companion: ALDHA Thru-hikers Companion, guidebook for the Appalachian Trail

The Complete Walker: Popular 1968 book by Colin Fletcher that dramatically expanded interest in backpacking

Contour lines: Curved lines on a map representing constant elevations above sea level

Contouring: Also sidehilling or slabbing, following a roughly constant elevation path around a mountain or canyon

Cornice: Dangerous overhanging ledge of snow and ice on a ridge or peak

Corridor: Narrow strip of land along both sides of a trail

COSPAS-SARSAT: International organization that uses government satellites to locate PLB rescue signals and trigger rescues

Cottage gear: Backpacking gear made by small companies, usually owned and operated by the founders

Cotton world: Off-trail life, when wearing cotton is not potentially life-threatening

Cove: Small bay or coastal inlet; also small valley in the Appalachian Mountains, closed at one or both ends

Cowboy camp: Sleep out in the open, without a tent or shelter

Cowboy coffee: Mixture of hot water and ground coffee carefully poured unfiltered into a cup

Cowboy water: Also dip-and-sip, drink water directly from the source without treatment

Cowpie: Also cow plop, meadow wafer, pasture pastry, flattened cow poop, avoid stepping on

Cowtaminated: Water source polluted by cattle waste

CPR: Cardiopulmonary respiration, first aid for reviving a few mostly dead patients

Crampons: Metal frame with spikes and straps, used on boots for climbing steep ice

Crevasse: Deep, dangerous crack in a glacier that can be hidden by a weak snow bridge

Croo: Caretakers of Appalachian Mountain Club huts

Crotch gusset: Small fabric panel in pants allowing more range of motion

Crotch rot: Inflammation and often infection around the genitals

Crushing miles: Also pushing miles, hiking much farther than usual each day to reach a goal

Crypto: Cryptosporidium, waterborne intestinal parasite that causes diarrhea

CT: Colorado Trail, 490-mile (780 km) trail through the Rocky Mountains from Denver to Durango, Colorado

Culvert: Water passage under a trail or road, made of pipe, rock, or wood

Cupholders: Backpack lower side pockets used to carry water bottles

Cushy: Comfortable

CX: Cross-country, also freehike, hike a path not on established trails

CYTC: Calendar Year Triple Crown, complete the PCT, CDT, and AT in one year between January 1 and December 31

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D

D: Denier, pronounced den-year, measure of thread and fabric density, higher is heavier

Daisy chain: Two-layered webbing with one layer sewn to leave open loops, used for hammock suspensions; also a long rope gathered using interlocking loops

DAM: Down-filled Air Mattress, inflatable sleeping pad insulated with down

Data Book: Appalachian Trail information published by the ATC

DCF: Dyneema Composite Fabric, fabric made with Dyneema

DCH: Dyneema Composite Hybrid, fabric made with DCF, bonded to layers of other materials

Dead branch tattoo: Also rock tattoo or trail tattoo, scar acquired while hiking

Dead fall: Dead tree laying across a trail

Death march: Long, boring hike, often in hot weather

Declination: Also magnetic declination, difference between true north and magnetic north

DEET: Type of chemical insect repellant applied to skin

Deets: Details

Derecho: Long line of intense, damaging windstorms

Diablo wind: Strong, hot, dry offshore wind in Central California

DIAD: Done In A Day

Dialed-in: Describes gear well matched to the task

Dirtbagging: Backpacking on a limited budget using ragged gear

Dispersed camping: Camping away from established campsites and trails

Ditty bag: Small bag to hold miscellaneous items

DIY: Do It Yourself

DOC: Dartmouth Outing Club

Dodgeway: Fence opening that permits hikers to pass, not livestock

Dome tent: Shelter shaped roughly like half of a ball

Double blaze: Two aligned vertical blazes indicating a sharp trail turn

Double-track: Primitive dirt road formed by parallel vehicle tires

Double-triple: Completing the Triple Crown twice

Double-wall: Tent with two layers of fabric overhead, outer layer waterproof

Down in the weeds: Focused on details, missing larger features

Down the rabbit hole: Getting deep into a topic, sometimes ending up somewhere strange

Downburst: Blast of air coming down from above, often during a thunderstorm

Droppin trou: Said to others before lowering shorts, pants, or trousers outdoors

Drumlin: Long low hill formed by glaciers

Dry camp: Camp overnight without using local water

Duct tape: Also Duck Tape brand name, wide, heavy duty tape used for repairs and other tasks

Duff: Layer of leaves, sticks, and other dead plant material covering the ground

Dust devil: Tiny tornado that picks up dust, mostly harmless

DWR: Durable Water Repellant, coating that helps rain run off fabric for a while

Dyneema: previously Cuben, brand of UHMW polyethylene fibers

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E

EABO: Eastbound thru-hiker

ECT: Eastern Continental Trail, 4,400 mile (7,100 km) route from Key West, Florida to Belle Isle, Newfoundland

EE: Enlightened Equipment, company that makes backpacking gear

EGNOS: Satellite system that improves Galileo accuracy in Europe, like WAAS for GPS in North America

Elk duds: Elk poop that resembles Milk Duds candy

EMS: Emergency Medical Services like paramedics and ambulances; also Eastern Mountain Sports outdoor retailer

EN rating: Also sleeping bag rating, unreliable sleeping bag low temperature estimate using the ISO 23537 standard, formerly EN 13537

End-to-ender: Someone completing the entire Appalachian Trail

ESBIT: Brand of hexamine solid fuel tablet

Escape velocity: Courage to leave a vortex

Escarpment: Long series of cliffs, roughly the same height and running the same direction

EtOH: Ethanol, drinking alcohol

Exposure: steep area with high risk of falling and serious injury or death, more exposure is more dangerous

External frame pack: Backpack with stiff supports near your back and outside the fabric

Extension collar: Extra-tall backpack body unrolled to carry more stuff

Eyelet: Shoelace hole in a boot or hiking shoe, often reinforced with metal or plastic

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F

F: Fahrenheit, U.S. measure of temperature, 32 F is 0 C, 86 F is 30 C

Facilatrees: Forest as toilet or “facilities”

FAK: First Aid Kit

Fall line: Shortest and steepest way down a hill

False lead: Path that looks like the real trail, but is not

False pass: Mountain crossing that looks like the true pass until you get there

False summit: High spot that looks like the true summit until you get there

FarOut: Formerly Guthook, brand of app-based guides to long-distance trails

Fastpacking: Covering many miles (km) per day with a very light backpack

FBC: Freezer Bag Cooking, preparing food by adding hot water to ingredients inside a thick zippered plastic bag

Fill power: Measure of down insulation fluffiness, higher is lighter

Firenado: Also fire whirl, tornado of fire formed during intense blazes

First-hand experience: Personally observed or participated in the subject

First Known Time: Time taken by the first person to complete a trail

FKT: Fastest Known Time, speed record for hiking a trail end to end

Flash drought: Drought that forms in days or weeks rather than years

Flash flood: Rapid flooding of low lying areas, often scouring desert washes and slot canyons in sunny conditions

Flip-flop: Thru-hike part of a trail in one direction, then skip ahead to hike another part in the other direction

Floater: Tiny debris suspended in water

Floorless: Tent without a built-in floor

Flophouse: Cheap town lodging for thru-hikers

Florida Trail: A 1,500 mile (2,400 km) trail following most of the length of Florida

Food fantasies: Backpacker dreams of what they will eat in town

Footprint: Separate floor underneath a tent for added protection

Ford: Cross a river by wading through the water

Four state challenge: Hike the Appalachian Trail across Virginia, West Virginia, Maryland, and Pennsylvania in less than 24 hours

Frameless: Backpack without an internal or external frame

Freestanding tent: Tent that mostly works without stakes in the ground

Frost quake: Also ice quake, earth shaking caused by ice suddenly cracking

FSO: From Skin Out, total pack weight plus everything worn or carried

ft: Foot, about 30.5 cm, exactly 12 inches

ft³: Also ft3, cubic foot, about 7.5 gallons or 28 liters, exactly 1,728 cubic inches

Fun factor: Current lack of enjoyment, part of evacuation decisions after illness or injury

FWIW: For What It’s Worth, slightly off-topic but still important

FWOT: Freaking Waste Of Time, project or path that seriously fails to meet expectations

FWS: Fish and Wildlife Service, U.S. Government agency managing over 235,000 square miles (over 600,000 km²) to protect wildlife

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G

g: Gram, about 0.035 ounces weight, 1 ounce is 28.35 g

GAIA GPS: App for mapping and navigating backcountry adventures

Gait: Walking pace

Gaiters: Lower leg and shoe coverings to protect from dirt, water, snow, and obnoxious plants

Galileo: European satellite navigation system like GPS

Gallon: About 3.79 liters, exactly 4 quarts

GAMEr: Northbound Appalachian Trail thru-hiker traveling from Georgia to Maine

Garvey: Double vertical blaze with the top blaze pointing to a trail turn

GAS: Gear Acquisition Syndrome, problem of buying too much backpacking gear

Gathered end: Hammock with each end gathered for suspension

Gathering: Annual ALDHA meetup in New Hampshire or West Virginia

GBITS: Great Backpacker In The Sky, mythical being who tests the toughness of hikers

GCNP: Grand Canyon National Park in Arizona

GDT: Great Divide Trail, 700-mile (1,130 km) trail in the Rocky Mountains along the border of Alberta and British Columbia

Gear attic: Fabric shelf high inside a tent for storing gear

Gear head: Someone very focused on backpacking gear

Gear: Backpacking equipment

Gearly afflicted: Backpacker with Gear Acquisition Syndrome

GET: Grand Enchantment Trail, 770-mile (1,240 km) route across Arizona and New Mexico

Getting off: Temporarily or permanently leaving a thru-hike

GG: Granite Gear or Gossamer Gear, companies that make backpacking gear

Ghost blazing: Following an abandoned trail segment

GGG: Gathering of the Gear Geeks, annual meetup of Backpacking Light gear heads in California; also Garage Grown Gear outdoor retailer

Giardia: Waterborne intestinal parasite that causes giardiasis, including diarrhea, stomach cramps, and vomiting

Ginourmous: Extremely large, bigger than enourmous

Glissade: Sliding down steep snow without skis, usually holding an ice axe to stop safely

Globalstar: Satellite system for messaging and phone calls; also a brand of satellite phones

GLONASS: Russian satellite navigation system like GPS

Glutes: Large muscles in the back of each thigh

GMC: Green Mountain Club

Gnarly: difficult, unpleasant, twisted, or excellent, depending on context

GNSS: Global Navigation Satellite Systems, like GPS, Galileo, GLONASS, and BeiDou

Go-to gear: Equipment used on most backpacking trips by someone

Going to ground: When a hammock camper decides to sleep on the ground

GORP: Good Old Raisins and Peanuts, also trail mix

GPS: Global Positioning System, U.S. satellite navigation system

GPX: Computer file with waypoints, tracks, routes, elevations, and times

Grade: Trail steepness, higher grades are steeper

Gram weenie: Also weight weenie, someone very focused on reducing their backpacking gear weight

Graupel: Also snow pellets, tiny, soft hail that can lead to avalanches later

Gray water: Dirty dishwater

Green tunnel: Most of the heavily-forested Appalachian Trail

Grom: Young participant in an extreme sport

Ground control: Off-trail people helping thru-hikers with shopping, shipping, bill paying, and pet care

Groundling: Also ground dweller or grounder, backpackers who sleep on the ground

GSMNP: Great Smoky Mountains National Park in North Carolina and Tennessee

Guesstimate: Estimate based on guesswork, calculation, and experience

Gully: Also gulch, large ditch to small valley formed by erosion

Gut it out: Keep going despite fatigue, illness, or injuries

Gut rot: Belly pain from bad food or infection

Guylines: Cords used to attach tents and tarps to stakes or other supports

GWL: Great Western Loop, 6,875 mile (11,065 km) route linking the PCT, PNT, CDT, GET, and AZT through nine states

GWT: Great Western Trail, 4,455 mile (7,170 km) trail from Mexico to Canada through Arizona, Utah, Wyoming, Idaho, and Montana

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H

ha: Hectare, about 2.5 acres

Haboob: Wide, intense dust storm pushed ahead by a storm front

HACE: High Altitude Cerebral Edema, life-threatening brain illness caused by altitudes above 8,000 feet (about 2,400 m)

Half gallon challenge: Eat a half gallon (about 1.9 liters) of ice cream halfway through the Appalachian Trail

Hammock: Fabric sling hung between trees, just above the ground, for sleeping

Hammock tent: Hammock with everything needed for shelter, including tarp, bug net, and suspension

Hamstring: Back thigh muscles running from hip to knee

Hanger: Hammock camper

HAPE: High Altitude Pulmonary Edema, life-threatening lung illness caused by altitudes above 8,000 feet (about 2,400 m)

Happy camper: Someone happy in their current activity

Hardcore: Very dedicated person

Hardshell: Waterproof jacket or pants without insulation

Harpers Ferry: ATC headquarters town near the Appalachian Trail in West Virginia

Hayduke Trail: 812 mile (1,307) route across Utah and Arizona

HE pot: Also HX pot, heat exchanger pot, with outer fins to capture more stove heat

Headlamp: Small light attached to a strap, usually worn on forehead or upside-down on neck

Headwall: Cliff at the upper end of a cirque

HEET: Brand of gasoline additive, sometimes used as alcohol stove fuel

Heine pot: Tall Heineken beer can turned into a cook pot

Hermit hiker: Someone who likes to hike alone

HH: Hydraulic head, unreliable measure of fabric water resistance, higher is more waterproof

High Sierra Camps: Permanent backcountry camps in Yosemite National Park, California, with tent cabins, bedding, and hot meals

Highway tree: Fallen tree that allows cross-country hiking over brush

Hiker box: Box or cabinet where thru-hikers donate unwanted stuff

Hiker funk: Persistent odor of thru-hiker clothing and gear after weeks of backpacking

Hiker Heaven: PCT thru-hiker hostel in Southern California

Hiker hunger: Intense hunger and enormous appetite developed while thru-hiking

Hiker midnight: 9 pm (2100 hours), bedtime for many thru-hikers

Hiker shuffle: Awkward thru-hiker steps after removing their backpack at the end of the day

Hiker tan: Dirty skin that resembles a suntan

Hiker trash: Affectionate name for thru-hikers after weeks of backpacking

Hiker-friendly: Town or business that appreciates thru-hikers

Hill-walking: Hiking in the hills

Hitchhike: Also hitch, get vehicle rides from strangers

HMG: Hyperlite Mountain Gear, company that makes backpacking gear

Home free: Very close to the end of a thru-hike

Hostel: Low-cost shared lodging often used by thru-hikers

HST: High Sierra Trail, 49-mile (79 km) trail through Sequoia National Park to Mount Whitney, California

HTD: Horizontal Tree Drip, when condensation drips from trees, then wind blows it into your face or tent vents

HTH: Hope This Helps

Hump: Carry a heavy load

Hut: Also bothy, permanent trail shelter, often shared with other backpackers

Hybrid tent: Combination single-wall and double-wall tent

Hydration bladder: Also water reservoir, flexible water container

Hydration system: Backpack-mounted hydration bladder, hose, and bite valve for hands-free drinking

HYOH: Hike Your Own Hike, resist pressure to hike or backpack like others, not permission to break rules

Hyperthermia: Dangerously high body temperature

Hyponatremia: Dangerously low blood sodium, usually from drinking too much plain water

Hypothermia: Dangerously low body temperature

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I

IANAL: I Am Not A Lawyer, warning that legal advice might not be correct

IAT: International Appalachian Trail, 1,850 mile (2,540 km) trail from the Appalachian Trail north end in Maine to the north tip of Newfoundland

Ice axe: Axe with one pointed head, one flattened head, and a foot spike, for climbing and crossing ice

Icebergs: Large rocks placed in overused campsites to prevent camping

ICT: Idaho Centennial Trail, 1,311 mile (2,110 km) trail across Idaho from Nevada to Canada

IERCC: Private company that coordinates responses to satellite communicator rescue messages

IIRC: If I Recall Correctly

IMO: In My Opinion

IMHO: In My Humble Opinion

IMNSHO: In My Not So Humble Opinion

in: Inch, about 2.5 cm

Indian summer: Warm dry autumn weather, typically after a period of cooler weather

inReach: Brand of two-way satellite communicators

Internal frame pack: Backpack with stiff supports near your back and inside the fabric

Inverted canister: Remote canister stove with preheat tube that can burn fuel from an upside-down canister in cold temperatures

Iridium: Satellite system for messaging, phone calls, and Internet access

IRL: In real life, usually back in town, versus the current setting

ISO: International Standards Organization, creates and publishes standards used to test backpacking gear

IT band: Part of the outer thigh that helps stabilize the knee; overuse while hiking can cause severe pain

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J

JMT: John Muir Trail, 211-mile (340 km) trail through the Sierra Nevada from Yosemite Valley to Mount Whitney, California

Jungle hammock: Hammock with built-in bug netting

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K

Karst: Eroded limestone landscape with sinkholes, caves, fissures, and towers

Katabatic wind: Wind caused by colder, denser air falling from a higher elevation

Katahdin: Appalachian Trail north end on Mount Katahdin, Maine

KCHBR: Kings Canyon High Basin Route, 124-mile (200 km) route in Sequoia-Kings Canyon National Park, California

kg: Kilogram, about 2.2 pounds

km: Kilometer, about 0.6 miles

km²: Also km2, square kilometer, about 247 acres or 0.4 square miles

Knob: Prominent rounded hill or mountain

Knot: Fixed looping of a rope, guyline, or webbing; common backpacking knots include half hitch, bowline, and taught line hitch

Krumholtz: Stunted and twisted trees found near treeline

Kula Cloth: Brand of pee cloth

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L

L: Liter, about 1 quart or 61 cubic inches

LASH: Long Assed Section Hike, backpack multiple sections of a longer thru-hike

Lash point: Small loop or slots on gear to attach other gear with straps or cord

lb: Pound, about 454 g, exactly 16 ounces weight

LCT: Lost Coast Trail, 25-mile (40 km) trail in California following the Pacific Ocean

Lean-to: Permanent backcountry shelter with slanted roof and open sides

Leapfrog: Repeatedly pass and get passed by the same backpackers while hiking

Learning opportunity: Mistake that you can learn from

Leeward: Also lee, downwind, the direction the wind is going toward

Litter: Trash left in the backcountry; also long, narrow rigid basket used to carry an injured person

LNT: Leave No Trace, guidelines to reduce local environmental impacts while backpacking

Loft: Thickness of fluffed-up insulation, like a sleeping bag ready for use, higher is warmer

Logbook: Also register, trailside paper book to record trail progress and communicate with other hikers

Lollipop: Hike that includes both an out-and-back and a loop

Looks good on paper: In theory this should work, reality might have other plans

LP: Lone Peak, brand of trail running shoes

Long Trail: 273-mile (439 km) trail through Vermont

The Look: Thru-hiker appearance after weeks of backpacking, with confidence, determination, and a muscular, lean body

Lyme disease: Serious illness transmitted to humans by tick bites

L2H: Lowest to Highest, 130 mile (209 km) route from Badwater to Mount Whitney in California

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M

m: Meter, about 1.1 yards or 3.3 feet

MacGyver: Creatively solve a problem using available materials, from an old TV series

mAh: milliamp hour, vague and confusing battery energy unit, use watt-hours (Wh) instead

Mail drop: Supplies and gear shipped to a thru-hiker for resupply along the trail

Massif: Distinct local group of connected mountains

MATC: Maine Appalachian Trail Club

MEC: Mountain Equipment Company, formerly Mountain Equipment Co-op, outdoor retailer

McLeod: Combination rake and hoe for trail building and firefighting

MEGA: Southbound Appalachian Trail thru-hiker, traveling from Maine to Georgia

Menstrual cup: Small soft reusable cup worn internally to catch menstrual blood, instead of using disposable tampons or pads

Meths: Also methylated spirits, denatured alcohol, often with methanol plus ethanol

Micro USB: Small rectangular connector used for recharging batteries

Microburst: Very localized blast of air from above, often during a thunderstorm

Mid: Pyramid-shaped tent supported by internal vertical poles

Mile: About 1.6 km

Mineral soil: Ground with almost no burnable material, good for stoves

Misery index: Scale of 1 to 10 measuring backpacker suffering, where 10 is worst

Misting: Water droplets floating inside a tent

ml: Milliliter, about 0.2 teaspoons, 1 teaspoon is about 5 ml

MLD: Mountain Laurel Designs, company that makes backpacking gear

Mod: Modify gear after purchase

Modder: Someone who modifies gear

Monkey butt: Red butt inflammation and often infection

Monsoon: Summer thunderstorm season in American southwest deserts

Moraine: Ridge of broken rocks formed by glaciers

Moulder strip: Also heat shunt, metal strip that carries heat from stove flames to a canister for better cold weather performance

Mountain money: Also shit tickets, toilet paper

Mountain walking: Hiking in the mountains

Mountains-to-Sea Trail: 1,175 mile (1,891 km) trail from the Great Smoky Mountains to the Atlantic Ocean through North Carolina

Mouse hanger: Cord through an empty can for hanging packs, to prevent mice from crawling down

MPD: Miles Per Day, 1 mile is about 1.6 km

MRE: Meal Ready to Eat, also Meal Rejected by Everyone, compact well-preserved military food

MRT: Mogollon Rim Trail, 500-mile (800 km) route following the Mogollon Rim across Arizona

MSR: Mountain Safety Research, company that makes backpacking gear

Moskies: Also muskies or mozzies, mosquitos

Multi-use trail: Trail with multiple uses allowed, like hiking, horseback riding, and mountain biking

MVTR: Moisture Vapor Transfer Rate, poorly-standardized measure of fabric ability to allow humid air to escape, higher allows more

MYOG: Make Your Own Gear, instead of buying gear made by others

MYTH: Multi-Year Thru-Hike, backpacking another part of one long-distance trail, year by year

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N

Nalgene: Brand of water bottle

National Scenic Trail: Eleven significant U.S. trails including the PCT, CDT, and AT

NCT: North Country Trail, 4,800 mile (7,700 km) trail from Vermont to North Dakota

Nero: Short day thru-hiking with just one night in town, nearly a zero day

Nest: Hammock camper setup including hammock, suspension, tarp, and insulation

Nesting: When one pot or cup fits nicely inside another

Newbie: Also noob, someone new to an activity

NNML: Northern New Mexico Loop, 500-mile (800 km) route through New Mexico

No-see-um: Also midge, tiny biting fly; also tent netting with holes too small for midges

NOBO: Northbound thru-hiker

NOC: Nantahala Outdoor Center

NOLS: Non-profit school teaching outdoor skills and wilderness medicine

Non-freestanding tent: Traditional tent that needs stakes in the ground

Nor'easter: Also Northeaster, intense blizzards ranging from North Carolina to Nova Scotia

NPS: National Park Service, U.S. Government agency that manages over 133,000 square miles (over 340,000 km²) “unimpaired for the enjoyment of future generations”

NWS: National Weather Service, U.S. Government agency that forecasts weather

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O

OCT: Oregon Coast Trail, 425-mile (684 km) trail along the Pacific coast in Oregon

ODT: Oregon Desert Trail, 750-mile (1,207 km) trail across the deserts of eastern Oregon

Off-trail: Hiking a path not on established trails; also the developed world away from a thru-hike

OHT: Ozark Highlands Trail, 320-mile (515 km) trail across northern Arkansas

OIA: Outdoor Industry Association, trade group of outdoor gear manufacturers

Old-growth: Ancient forest or tree not yet logged

On-trail: Hiking on an established trail

OP: Original Post, referring back to the first entry in a forum thread

OR: Outdoor Research, company that makes backpacking gear; also Outdoor Retailer, annual trade show

Oregon challenge: Thru-hike the PCT all the way through Oregon in less than 2 weeks

OTC: Over The Counter, medicines like aspirin that you can buy without a prescription

Out-and-back: Hike out then return on the same trail

Outer tent: Rainfly on a double-wall tent

Outhouse: Also privy, small permanent shelter with a hole in the ground for pooping

Over-the-top: Exaggerated or excessive

Overpronation: Pushing off from the big toe while hiking, often causing foot problems

oz: Ounce, about 28.4 g weight; also about 28.4 ml volume

Oz: Australia

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P

Pack it out: Leave nothing behind on a backpacking trip

Pack string: Pack animals like horses or mules, tied together and led down the trail

Packing your fears: Carrying more gear and food than needed due to fears and inexperience

Packraft: Also trail boat, one-person, lightweight, inflatable boat designed to be carried and used by a backpacker

Packsplosion: Also full yard sale, emptying a pack and spreading everything out to find something

Pass: Mountain ridge low point, sometimes allowing hiking to the other side

Patagucci: Nickname for Patagonia, company that makes backpacking gear

PBC: Portable Battery Charger, also battery bank, USB brick, and many variations, battery pack for recharging other devices using USB

PCT: Pacific Crest Trail, 2,650-mile (4,270 km) trail through California, Oregon, and Washington from Mexico to Canada

The PCT Hiker’s Handbook: Influential 1992 book by Ray Jardine that re-kindled interest in lightweight backpacking, MYOG, and corn pasta

PCT-L: Pacific Crest Trail email list and archive

PCTA: Pacific Crest Trail Association, issues PCT permits and maintains the trail

PCT Days: Annual Pacific Crest Trail festival in Cascade Locks, Oregon

Peak bagging: Climbing a list of mountain peaks

Pee: Liquid body waste, urine

Pee cloth: Also pee rag, cloth used to wipe body after squatting to pee, then hung outside a backpack to dry

Penalty potatoes: Food carried but not eaten on a trip

Pepsi can stove: Also tin can stove, alcohol or solid fuel stove made from an empty can, like cat food, tuna, or beer

PEU: Also PE, polyether urethane, waterproof fabric coating

PF: Plantar fasciitis, painful foot condition

PFD: Personal Flotation Device, lifejacket

PhD: Posthole Digger, hiker who enjoys postholing through the snow

Piezo igniter: Makes electric sparks by clicking a button, used for lighting stoves

PIF: Pay It Forward, encourage someone you helped to help someone else in return

Pinhoti Trail: 335 mile (539 km) trail in the Appalachian Mountains through Georgia and Alabama

Pit zips: Jacket armpit zippers allowing more ventilation

PITA: Pain In The Ass, obnoxious person or task

Plantar fasciitis: Painful inflammation of the foot arch

Platypus: Brand of hydration bladders

Playing in the high energy zone: Engaging in outdoor activities with dangerous natural forces, like hiking precarious ridge tops or cornices, or boating difficult river rapids

PLB: Personal Locator Beacon, one-time-use device that sends rescue signals through government satellites

Plunge step: Also heel step, hike down a snowy or crumbly slope heel-first, digging in with each step

PNT: Pacific Northwest Trail, 1,200-mile (1,900 km) trail from the Rocky Mountains in Montana to the Pacific Ocean in Washington

PO: Post Office, where thru-hikers send and receive mailed packages

Pogonip: Also ice fog, freezing fog that often coats tree branches and other surfaces

Point: First person in a group of hikers, responsible for finding the way

Polycro: Also polycryo, lightweight plastic sheeting used as tent footprints

Poop: Also poo, semi-solid body waste, feces, excrement, manure

PORE: Point Reyes National Seashore in California

Posthole: Plunge feet and legs deep into snow while hiking

Pot cozy: Insulation around a pot, keeps food warm after heating

Potable water: Water clean enough to drink

Potty trowel: Small one-handed shovel for digging cat holes

POUS: People Of Unusual Size, backpackers taller than most, adapted from a Princess Bride movie scene

Power hiker: Backpacker who covers many miles per day, often in the dark

PRD: Pocket Rocket Deluxe, an upright canister stove made by MSR

Preheat tube: Stove fuel tube that crosses the flames for better cold weather performance

Prescribed fire: Also controlled burn, fire set under supervision to prevent larger wildfires

pt: Pint, about 473 ml, exactly 2 cups or 16 ounces volume

PU: Polyurethane, also polyester urethane, waterproof fabric coating

PUD: Pointless Ups and Downs, also Mindless Ups and Downs, trail segments that seem to climb and drop for no reason

Puffy: Thick insulated jacket that looks puffy

Pulaski: Combination axe and adze for trail building and firefighting

Pull the trigger: Decide to buy a piece of gear after lengthy thinking

Purist: Appalachian Trail thru-hiker planning to pass every white blaze

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Q

q: Quart, about 946 ml, exactly 2 pints, 4 cups, or 32 ounces volume

Quad: Also quadrangle, uniquely named USGS topographic map covering a rectangular area

Quilt: Hoodless, bottomless sleeping bag, like a very warm blanket

Quiver: Personal collection of similar backpacking gear, like several backpacks

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R

R-value: Standardized measure of sleeping pad insulation, higher is warmer

r/Ultralight: Reddit online ultralight backpacking community

Rain gear: Clothing worn for rain protection, including hat, jacket, mittens, and pants

Rain shadow: Area with much less rain downwind of a mountain range, often creating deserts

Rainbow blazer: Appalachian Trail thru-hiker who hikes different-colored blazed routes

Rainfly: Also flysheet, separate waterproof tent layer designed to shed falling rain and snow

Ramen bomb: Meal combining ramen noodles and instant mashed potatoes

Ray Day: Best date to hike out of Kennedy Meadows on a northbound PCT thru-hike, considering Sierra Nevada snow depths

Ray-way: Backpacking philosophies of author Ray Jardine

Real world: Backcountry or civilization, depending on context, like “back in the real world ...”

Red flag warning: National Weather Service forecast of high fire danger

Red snow: Snow colored by red algae, not safe to eat or drink

REI: Recreational Equipment Inc, very large U.S. outdoor retailer

Relo: Relocated trail segment

Remote canister stove: Stove with a short hose that connects to a fuel canister

Repeat offender: Someone thru-hiking the same long distance trail again

Reroute: Trail moved to an adjacent or newly-built trail section

Rescue assistance: Prepaid service that helps with rescues after you contact them

Rescue insurance: Insurance that pays for rescues after the incident

Resupply: When thru-hikers pick up more supplies

RICE: Rest, Ice, Compression, Elevation, memory aid for treating injuries like sprains and broken bones; instead of compression, use support like tape or splints

Ridge runner: Person employed to hike back and forth on trail sections, educating hikers and enforcing rules

Ridgeline: Line following the highest points of a ridge; also a tight guyline above a hammock to maintain desired shape

Ridgerest: Brand of closed-cell-foam sleeping pad that rolls up

Rime ice: Ice formed on trees and other surfaces when windblown water droplets freeze

RMC: Randolph Mountain Club

Rock garden: Part of a trail or river with lots of rocks sticking up

Rock hop: Hop from rock to rock across a river trying to stay dry

RSN: Real Soon Now, eventually or someday

RUA: Restricted Use Area, backcountry area with special rules

Ruck: Meetup of outdoor enthusiasts

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S

S2S: Sea-to-Summit, company that makes backpacking gear

Safety meeting: People smoking marijuana together

SAK: Swiss Army Knife, brand of pocket knife with other tools

SAM splint: Brand of shapable but rigid support for suspected broken bones

Santa Ana wind: Strong, hot, dry offshore winds in Southern California

SAR: Search and Rescue, the team and process of finding people and rescuing them

Scat: Animal poop

Scouting: Inspecting the route ahead from a high point along a trail or river; also a worldwide youth movement teaching outdoor activities including backpacking

Scramble: Climb a rugged area using hands and feet, but not rock climbing

Scree: Fist-sized rocks on slopes, difficult to hike over

Seam tape: Special tape added to tent, backpack, or rainwear seams for waterproofing and reinforcement

Second breakfast: Extra morning meal due to hiker hunger

Second dinner: Extra evening meal due to hiker hunger

Section: Portion of a longer thru-hike, usually between towns or major trailheads

Section hiking: Backpacking sections of long trails like the PCT, CDT, or AT

SEKI: Sequoia and Kings Canyon National Park in California

SEND: Satellite Emergency Notification Device, satellite communicator that sends rescue messages through commercial satellites

Shakedown: Gear inspection and suggestions from a more experienced backpacker

Shakedown hike: Backpack trip to test gear and skills before a longer hike

Shale: Loose flat rocks with sharp edges, often difficult to hike over

Shell: Uninsulated outermost clothing, like a rain jacket or windjacket

Shelter: Tent or tarp; also small three-sided building for backcountry camping

Shelter rat: Hiker who camps only in permanent shelters

Shenandoah: Shenandoah National Park in Virginia

Shin-splints: Shin pain from overuse and inflammation

SHR: Sierra High Route, 195-mile (314 km) route above timberline in the Sierra Nevada, California

SHS: Shaky Headlamp Syndrome, annoying lighting changes as your head moves while wearing a headlamp

SHT: Superior Hiking Trail, 310-mile (500 km) trail following the shore of Lake Superior in Minnesota

Shuttle: Paid ride between trailhead and town

Siberian express: Cold air mass from Siberia crossing North America

Silicone: Plastic made with silicon, used in backpacking gear from spoons to fabric coatings

Sil/PU: Fabric coated with with silicone on one side, polyurethane on the other

Sil/sil: Fabric coated with with silicone on both sides

Silnylon: Silicone-coated nylon fabric

Silpoly: Silicone-coated polypropylene fabric

Single-track: Narrow trail

Single-point hammock: Also portaledge, hangs from one overhead point, mostly used for rock climbing

Single-wall: Tent with only one upper fabric layer

Skipping: Bypassing a section of trail

Skunked: When cars do not stop while hitchhiking

Skyhook: Mythical device for suspending items in midair; also a rock climbing device

Slackpacking: Sending a backpack ahead while hiking without it

Sleep system: Sleeping bag or quilt plus sleeping pad

Slogging: Difficult hiking on a muddy trail

Slot canyon: Long narrow channel eroded into the earth, typically in the southwestern U.S.

SMD: Six Moon Designs, company that makes backpacking gear

Smoke shifter: Mythical device for moving campfire smoke, often requested as left-handed or right-handed

Smokies: Part of the Appalachian Mountains on the border of Tennessee and North Carolina

Snag: Standing dead or dying tree; also large chunks of wood in a river

Snot rocket: Plug one nostril and blow mucus forcefully out the other

Snowmageddon: Also snowpocalypse or snowzilla, extreme snow storms in the popular press

Snowpack: Compressed snow layered on the ground, usually from multiple storms, higher snowpack is deeper

SNP: Shenandoah National Park in Virginia

SOBO: Southbound thru-hiker

Social trail: Also use trail, unofficial trail formed by repeated walking

Softshell: Wind and water resistant insulated jacket or pants, not waterproof

Soloing: Backpacking alone

SOS: Emergency signal requesting help or rescue

Spectra: Brand of UHMW polyethylene fibers

Speed hiking: Hiking rapidly down a trail pursuing a new record

Spork: Combination spoon and fork in one utensil

SPOT: Brand of satellite phones and satellite communicators

Springer fever: Desire by previous thru-hikers to return to the Appalachian Trail

Springer Mountain: Appalachian Trail south end in Georgia

Spruce trap: Spruce tree covered by deep snow, dangerous to fall into

sq mi: Also mi² or mi2, square mile, about 259 ha, exactly 640 acres

Square meter: Also or m2, about 1.2 square yards or 10.8 square feet

Square yard: Also yd² or yd2, about 0.84 square meters, exactly 9 square feet

Stack height: Thickness of a shoe sole at a given point

Stats: Statistics and details

Stealth camping: Camping well off trail at an unofficial site, while practicing Leave No Trace

Stick snake: Stick that jumps up and hits you when you step on it

Stile: Steps passing over a fence that permit hikers to pass, not livestock

Stoveless: Backpacking without a stove, usually eating cold food

Stride: Walk with long steps

Stride length: Average step length while hiking, sometimes useful for navigation

Stupid light: Gear too light to function well; also not carrying enough to reach goals or stay safe

SUL: Super Ultra Light, base pack weight less than 5 pounds (2.2 kg)

Summit: Also peak, top of a mountain

Sun cups: Uneven snow surface like the inside of a giant egg carton, hard to hike over

Supination: Hiking with most weight on the outside of feet, often leading to pain

Suspension: Straps, ropes, and hardware needed to hang a hammock between trees

Swag: Lowest connection between two ridges

Swale: Dip in a trail designed to shed water

Swamp ass: Sweaty butt, can cause chafing and monkey butt

Sweep: Last hiker in a group, makes sure no one falls behind

Switchback: Sharp trail turn on a slope to make climbing and dropping easier but longer, and reduce trail erosion

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T

Talus: Large broken rocks that usually do not move as you step on them

TAR: Therm-a-Rest, brand of backpacking gear

Tarn: Mountain lake or pond scooped out by a glacier

Tarp: Simple overhead fabric shelter with no floor or doors

tb: Tablespoon, about 15 ml

TBD: To Be Determined, specification or answer will be supplied later

TBI: Traumatic Brain Injury, serious head injury typically caused by a hard impact like falling

TD: Trail Designs, company that makes backpacking gear

Teardown: Completely disassemble a piece of gear, often documenting the process with photos

Tehachapi challenge: Hike the Pacific Crest Trail from Hiker Town to Tehachapi, California in less than 24 hours

Ten essentials: Short list of items day hikers should carry for safety

Tenkara: Minimalist fly-fishing without a reel

Tent body: Inner fabric layer of a double-wall tent

Tent platform: Flat wooden stage or dirt pad for camping

Three-season: Gear and skills for spring, summer, and fall backpacking, loosely defined

Thru-hiking: Long, multi-day backpacking that requires resupply and usually starts and ends in different places

Thundersnow: Snow falling during thunder and lightning

Ti: Titanium

Ticks: Tiny blood-sucking parasites that can transmit Lyme disease and other serious infections

TNF: The North Face, company that makes backpacking gear

Tog: Clothing insulation measurement, about 0.645 clo or R 0.57

Togs: Clothing

Top quilt: Quilt used on top of a hammock camper or groundling

Topo: Topographic map with contour lines of constant elevation; also a brand of trail running shoes

Torso pad: Short sleeping pad just long enough to reach from head to butt

Town clothes: Clothing worn by thru-hikers while in town

Town gut: Belly pain after thru-hikers eat too much in town

TP: Toilet Paper, used to wipe your butt after depositing poop, instead of using a bidet

TPW: Total Pack Weight, combined mass of everything carried in a backpack

Trail angel: Someone who provides trail magic to thru-hikers

Trail clearing: Removing trail obstacles for easier passage

Trail Days: Annual Appalachian Trail festival in Damascus, Virginia

Trail gorilla: Volunteer who helps maintain the PCT

Trail legs: Stronger, almost tireless legs of thru-hikers after weeks of backpacking

Trail magic: Unexpected help or supplies provided to thru-hikers

Trail muffin: Horse manure on a trail

Trail name: Nickname traditionally given to a backpacker on their first thru-hike

Trail provides: Thru-hiker belief that when they really need something, it will appear

Trail runners: Lightweight trail-running shoes used instead of boots

Trail spice: Leaves, twigs, and dirt in backpacking food

Trail spikes: Also microspikes, metal spikes attached under trail runners for icy trails

Trail town: Hiker-friendly towns near popular long-distance trails

Trail virgin: First time thru hiker

Trailhead: Trail segment start and end, typically a parking lot or road

Tramily: Trail family, group of thru-hikers who bond and travel together

Tramper: Hiker, especially one who continues despite bad weather

Traverse: Hike horizontally across a slope; also hike the length of a mountain range, island, or named region

Tread: Bottom of a shoe or boot that contacts the ground; also the surface of a trail

Treadway: Constructed surface of a trail

Treeline: Maximum elevation or latitude where trees strop growing, replaced by shorter plants

Trekking: Hiking, usually long-distance hiking

Trekking poles: Also hiking poles or hand wands, hand-held poles used for stability and pushing forward

Triage: Sort multiple sick or injured patients into a few priority levels

Triangulation: Determine position using compass bearings to three landmarks like mountain peaks

Triple Crown: PCT, CDT, and AT

TRT: Tahoe Rim Trail, 175 mile (281 km) trail around Lake Tahoe in California and Nevada

ts: Teaspoon, about 5 ml

TSA: Transportation Security Administration, U.S. Government agency with rules about what you may not take on an airplane, enforced through inspections at airports

TST: Theodore Solomons Trail, 271 mile (437 km) trail in the Sierra Nevada, roughly parallel to the John Muir Trail at lower elevations

TT: Tarptent, company that makes backpacking gear

Turnpike: Also highway or freeway, heavily used trail

Type 1 fun: Traditional fun, enjoyable during the experience

Type 2 fun: Miserable experience that seems like fun later, worth repeating

Type 3 fun: Terrible experience, usually requiring rescue or emergency medical care, avoid repeating

TYT: Tahoe-Yosemite Trail, 186 mile (299 km) route from Lake Tahoe to Yosemite National Park in California

Tyvek: Brand of waterproof non-woven polyethylene fabric

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U

UHMW: Also UHMWPE, Ultra-High-Molecular-Weight Polyethylene, very strong, lightweight, plastic fibers used in fabrics and guylines, like Dyneema and Spectra

UL: Ultralight, base pack weight less than 10 pounds (4.5 kg)

Underquilt: Quilt hung just below a hammock for insulation from cold air

Understory: Shorter trees and bushes growing beneath a taller forest

Undulating trail: Climbs up and down like a series of ocean waves

Unobtainium: Mythical substance that solves all problems

Upright canister stove: Small stove that sits top of a fuel canister

USB-A: Rectangular connector used for recharging batteries

USB-C: Oval connector used for recharging batteries

USFS: United States Forest Service, U.S. Government agency that manages over 300,000 square miles (over 780,000 km²) for multiple uses

USGS: United States Geological Survey, U.S. Government agency that makes topographic maps and measures river flows

UV: Ultraviolet, invisible sunlight that can tan skin and cause cancer

UV-C: Ultraviolet light that can sterilize water

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V

Varmint: Also varmit or vermin, troublesome person or wild animal

VBL: Vapor Barrier Liner, waterproof inner clothing or sleeping bag liner used below freezing

Vestibule: Sheltered tent entrance, often used to store gear

Virga: Visible rainfall that evaporates before reaching the ground

Vitamin I: Ibuprofen, non-prescription medicine for pain and inflammation

Vortex: Place that thru-hikers find hard to leave, like a town, restaurant, or hot springs

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W

W: Watt, standard unit of electrical power, not energy

WAAS: Satellite system that improves GPS accuracy in North America

Waffle-stompers: Heavy boots with lugged soles that leave waffle-like patterns on trails

WAG bag: Special bag used to carry poop out of heavily used backcountry areas

Walk-in: Developed campsites reserved for backpackers or bicyclists

Walk-up: Easy mountain summit, no more than Class 2 climbing

War wounds: Injuries earned while hiking

Washout: Also blowout, portion of trail destroyed by flooding or erosion

Water math: Calculating how much water to carry between possibly unreliable sources

Water report: Water source information posted online by other thru-hikers, like desert sections of the PCT and CDT

Waterbar: Log or rock barrier that directs water off a trail to prevent erosion

Waterproof: Fabric or container that resists the entry of water

Watershed: Landscape that channels all the rain, melted snow, and groundwater feeding into one stream or river

WEBO: Westbound thru-hiker

Weekend warrior: Also weekender, backpacker camping for 1 to 3 nights

WEMT: Wilderness Emergency Medical Technician, training and certification for backcountry medicine

Wet out: Saturated waterproof breathable fabric that stops breathing, then condensation builds up inside

WFA: Wilderness First Aid, training and certification for basic backcountry first aid

WFR: Wilderness First Responder, also woofer, training and certification for advanced backcountry first aid

Wh: Watt-hour, standard unit of electrical energy, not power

White blaze: Blaze that marks the one true Appalachian Trail

White blazer: Thru-hiker following only white blazes on the Appalachian Trail

Whites: White Mountains of New Hampshire

Whoopie sling: Lightweight hammock suspension adjusted using hollow rope sliding through itself

Widowmaker: Dead tree or large limb that could fall and injure or kill a backpacker

Wild: Book by Cheryl Strayed about her PCT thru-hike attempt, made into a movie starring Reese Witherspoon, the movie dramatically increased PCT traffic

Wilderness: Land cultivated by Native Americans before colonization and genocide, now unoccupied and undeveloped

Wilderness area: Highly protected roadless U.S. public lands, over 170,000 square miles (over 440,000 km²)

Williwaw: Also squamish wind, blast of cold wind dropping from the mountains

Wind direction: Compass direction the wind blows from, so an east wind blows from east to west

Wind layer: Outer clothing to protect from wind

Windchill: Additional cooling caused by wind

Windchill factor: Lower felt temperature computed from temperature and wind speed

Windjacket: Jacket to protect from wind

Windpants: Pants to protect from wind

Windward: Upwind, the direction the wind is coming from

WM: Western Mountaineering, company that makes backpacking gear

WMI: Now NOLS Wilderness Medicine, teaches backcountry first aid and medicine

Wonderland Trail: 93-mile (150 km) trail around Mount Ranier in Washington

WPB: Waterproof Breathable, fabric that might be both waterproof and breathable

WRHR: Wind River High Route, 95-mile (153 km) route across the Wind River mountain range in Wyoming

WTH: What the hell?, astonished at something

WTF: Very astonished at something

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X

XUL: Extreme Ultra Light, base pack weight even less than SUL

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Y

Yard sale: Backpacking gear unpacked and spread out, usually for drying

yd: Yard, about 91 cm, exactly 3 feet

Yellow blaze: Yellow center-line on a highway

Yellow blazer: Someone who hitchhikes around trail sections

Yellow snow: Snow colored by urine, “don't you eat that yellow snow”

YKK: Brand of zippers

YMG: Yama Mountain Gear, company that makes backpacking gear

YMMV: Your Mileage May Vary, worked for me, might not work for you

YNP: Yosemite National Park in California

Yogi-ing: Indirectly encouraging others to offer food or drink without asking, like the cartoon character Yogi Bear

Yo-yo: Hike a long trail in one direction, then turn around and hike back to the start

Yurt: Round semi-permanent tent-like shelter

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Z

Z Lite: Brand of closed cell foam sleeping pad that folds up

Zero day: Day with no miles thru-hiked, two nights in the same town for rest and resupply

Zero-drop: Shoe where the heel and toe are at the same stack height, typically small

Zero-mile: Beginning of a trail that might not be at a trailhead, like Springer Mountain for the Appalachian Trail

Zoleo: Brand of two-way satellite communicators

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0-9

10 by 10: 10 miles (about 16 km) by 10 am, strategy for hiking more distance per day

20, 25, 30, 40: Planned mileage today, like “hiking a 30”, 1 mile is about 1.6 km

2000-miler: Successful Appalachian Trail thru-hiker

911: Emergency phone number for the U.S., Canada, and several other countries, like 999 or 112 elsewhere

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Answering “What does that mean?” in clear, simple words. Designed for backpackers in America unfamiliar with some expressions, which might be regional or trail-specific. These are not comprehensive definitions. Many entries have other meanings depending on context. All trail lengths are approximate and subject to change.

Goals: Created by Rex Sanders, CC BY-SA 4.0
Over 860 entries as of 2024 October 5
https://backpackingjargon.com