The Collaborative International Dictionary of English v.0.48:

Collapse \Col*lapse"\, v. i. [imp. & p. p. Collapsed; p. pr. &
   vb. n. Collapsing] [L. collapsus, p. p. of collabi to
   collapse; col- + labi to fall, slide. See Lapse.]
   1. To fall together suddenly, as the sides of a hollow
      vessel; to close by falling or shrinking together; to have
      the sides or parts of (a thing) fall in together, or be
      crushed in together; as, a flue in the boiler of a steam
      engine sometimes collapses.
      [1913 Webster]

            A balloon collapses when the gas escapes from it.
                                                  --Maunder.
      [1913 Webster]

   2. To fail suddenly and completely, like something hollow
      when subject to too much pressure; to undergo a collapse;
      as, Maximilian's government collapsed soon after the
      French army left Mexico; many financial projects collapse
      after attaining some success and importance.
      [1913 Webster]