cirque

n. corrie, cwm, semicircular bowl-shaped hole with steep walls inside a hill or a mountain formed by glacial erosion (Geology); circle; circus (Archaic from French)

A cirque is an amphitheatre-like valley, or valley head, formed at the head of a glacier by erosion. A cirque is also known as a cwm in Wales, a coomb or coombe in England, and a corrie in Scotland and Ireland, although these terms apply to a specific feature of which several may be found in a cirque.
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Noun
1. a steep-walled semicircular basin in a mountain; may contain a lake
(synonym) corrie, cwm
(hypernym) basin

n. circus; amphitheatre; bedlam, chaos (Informal)

(n.)
A kind of circular valley in the side of a mountain, walled around by precipices of great height.
  

(n.)
A circle; a circus; a circular erection or arrangement of objects.