v.
   - (of a structure) suddenly fall down or give way. 
▸
[usu. as adj. collapsed]
 (of a lung or blood vessel) fall inwards and become flat and empty.
 - fall down as a result of illness or injury.
 - fail suddenly and completely.
 
n.
  - an instance of a structure collapsing.
 - a sudden failure or breakdown.
 
 
  Etymology
  C17: from medical L. collaps-, collabi, from col- ‘together’ + labi ‘to slip’.