Noah Webster's New International Dictionary of the English Language

1. (v. i.) 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.

2. (v. i.) 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.

3. (n.) A falling together suddenly, as of the sides of a hollow vessel.

4. (n.) A sudden and complete failure; an utter failure of any kind; a breakdown.

5. (n.) Extreme depression or sudden failing of all the vital powers, as the result of disease, injury, or nervous disturbance.