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.
A balloon collapses when the gas escapes from it.
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.