cave in

Noun

• the sudden collapse of something into a hollow beneath it

Verb

• 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
    

Related words

• Synonyms: 
  subsidence , collapse , fall in , give , give way , break , founder