Acute Mountain Sickness (AMS) – an illness caused by the lower pressure and oxygen content of higher altitude air, symptoms can range from mild to life threatening, and the risk of sickness is greater the faster a climber ascends
 
Altitude Acclimatization – the gradual process of becoming accustomed to the lower oxygen and air pressure found at higher altitudes, this process is key to preventing Acute Mountain Sickness

 
Approach Shoes – lighter weight comfortable hiking boots used for less demanding conditions
  
Avalanche – the rapid falling of a large mass of snow or rocks, sliding down the mountain, a very dangerous aspect of mountain climbing

Blisters – fluid-filled sores caused by friction between the skin and shoes, can be prevented or minimized by wearing good-fitting high-quality shoes 
 
Canyoneering – exploring canyons through hiking, climbing, rappelling, etc.

Chest Strap – a small strap of webbed material which clasps across the chest securing the shoulder straps, also called a “sternum strap”

Coasteering – exploring the coastal regions, hiking across beaches, dunes, lagoons, etc.

Compass --  a navigational aid containing a free-spinning magnetic needle, attracted toward the magnetic North Pole and enabling a hiker to discern which direction he or she is traveling in, see “Magnetic Declination” 
 
Conditioning Tights – a specially constructed piece of hiking equipment designed to give extra support to overworked muscle groups in the legs on strenuous hikes 

Crampons – spikes affixed to the bottom of mountain-climbing footwear for better traction when rock climbing, often found on “Mountaineering Boots”

Cross Hikers – a medium durability footwear designed for traction on terrain of mid-level difficulty