WordNet (r) 3.0 (2006):
cave in n 1: the sudden collapse of something into a hollow beneath it [syn: cave in, subsidence] v 1: break down, literally or metaphorically; "The wall collapsed"; "The business collapsed"; "The dam broke"; "The roof collapsed"; "The wall gave in"; "The roof finally gave under the weight of the ice" [syn: collapse, fall in, cave in, give, give way, break, founder]