As a Noun: 1. The destruction of a building by the roof and walls falling down. English = collapse. 2. The destruction of a tunnel or a cave by the ceiling and walls falling down. English = cave in. As a Verb or Adjective: 1. Of the roof and walls of a building, to suddenly fall down. English = collapse. 2. Of the ceiling of a tunnel or cave, to suddenly fall down. English = cave in, collapse.