Definition: break down, literally or metaphorically
Usage: 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
Main entry: fall in
Definition: to take one's place in a military formation or line
Usage: Troops fall in!
Definition: become part of; become a member of a group or organization
Usage: He joined the Communist Party as a young man