Terrain in which the consequences of an avalanche are especially hazardous, such as a gully, an abrupt transition, an avalanche path that terminates in trees, a crevasse field or a cliff.
Terrain Trap:

What will happen if it slides? The consequence of an avalanche is one of the most important factors in judging the danger of avalanche terrain. Bad consequences include trees (the “giant bread slicer”) a large cliff or a terrain trap. A terrain trap is a sharply concave part of the runout such as a gully, an abrupt transition or a crevasse where avalanche debris will pile up deeply. Since shoveling takes such a long time, deep burials have a very low chance of survival. Very few victims live from burials deeper than about 5 feet. Even a small avalanche off the side of a gully can have very deadly consequences.

Additional Terms:
Anchors Hard Slab Avalanche Slide
Aspect High Danger Sluff
Avalanche High Marking Snowpit
Avalanche Path Isothermal Soft Slab Avalanche
Avalanche Transceiver Layer, Snow Stability
Bed Surface Leeward Stability Test
Collapse Loading Starting Zone
Concave Slope Loose Snow Avalanche Stepping Down
Considerable Danger Low Avalanche Hazard Sun Crust
Convex Slope Melt-Freeze Snow Surface Hoar
Cornice Metamorphism, Snow Sympathetic Trigger
Corn Snow Moderate Danger Temperature Gradient
Couloir Persistent Weak Layers Terrain Trap
Cross Loading Point-Release Track
Crown Face Probe Trigger
Danger Ratings Propagation Trigger Point
Deep Slab Avalanche Rain Crust Upside-Down Storm
Density, Snow Remote Trigger Weak Layer
Depth Hoar Rime Weak Interface
Dry Snow Avalanche Runout Zone Wet Snow Avalanche
Extreme Danger Sastrugi Windward
Faceted Snow Settlement Wind Loading
Fracture Ski or Slope Cut Wind Slab
Glide Skinning, Skin Track Whumpf
Graupel Slab