Acute Mountain Sickness (AMS): a complex medical condition resulting from changes in altitude, characterized by symptoms such as dizziness, confusion, fatigue, headache, and shortness of breath.

Alpine Start: climbing a very early start for a climb, usually before sunrise, made in order to have the benefit of firm snow conditions or to utilize daylight

Avalanche: a rapid downhill flow of a large mass of snow or ice dislodged from a mountainside or the top of a precipice, or a similar fall of rocks and earth

Belay: climbing to fasten or control the rope to which a climber is attached by wrapping it around or through a metal device or another person

Bergschrund: a crevasse formed at the head of a glacier

Bivouac: a short, unplanned overnight stay, often with minimum equipment

Carabiner: an oblong metal ring with an openable spring-hinged side, used in rock and mountain climbing for such purposes as clipping a freely running rope to an anchor

Col: a low point in a ridge of mountains, often forming a pass between two peaks

Cornice: mountaineering an overhanging mass of snow or ice formed by wind action

Couloir: a broad mountain gully, especially one prone to avalanches

Crampons: a set of metal spikes that hook onto mountaineering boots and are used for ice climbing or glacier trekking

Crevasse: a deep crack in the ice of a glacier

Diamox (Acetazolamide): a drug used for the prevention and treatment of altitude sickness

French Technique: also known as Flat-Footing, it is an efficient means of climbing moderate to steep snow and ice where the feet are positioned across the hill; this technique minimizes the strain on leg muscles

Frostbite: damage to body extremities caused by prolonged exposure to freezing conditions, characterized by numbness, tissue death, and gangrene

Glacier: a large body of continuously accumulating ice and compacted snow, formed in mountain valleys or at the poles, that deforms under its own weight and slowly moves

Glissade: a controlled slide down a snowy slope made without skis by somebody in a standing or crouching position

High Altitude Pulmonary Edema (HAPE): a serious medical condition resulting from the accumulation of fluid in the lungs, caused by the lower barometric pressure and decreased oxygen levels that exist at high altitude

High Altitude Cerebral Edema (HACE): a serious medical condition caused by a buildup of fluid in the tissue around the brain at high altitude

Hypothermia: dangerously low body temperature caused by prolonged exposure to cold

Icefall: a face of a glacier on which the gradient is so steep that the ice breaks up into a jumble of blocks

Jumar (ascender): a clip or clamp used in rock climbing or ice climbing that runs freely up a slack rope but tightens around the rope in response to weight applied from below

Rappel: to descend a steep slope or vertical face using a rope that is secured at the top and passed through a rappel device

Scree: an accumulation of rock debris at the base of a cliff, hill, or mountain slope, often forming a heap

Self Arrest: stopping a fall on snow or ice by using an ice axe and crampons

Serac: a ridge, pinnacle, or block of ice in the crevasses or slope of a glacier

Sherpa: a member of a people originally from Tibet who live on the southern Himalayan slopes in Nepal and Sikkim (India). Sherpas are noted for their mountaineering skills

Sirdar: Head Sherpa on an expedition

Verglas: a thin coating of ice found on rock or exposed ground