1 fall (down or in or apart), crumple, cave in, deflate, crumble, tumble down, break down, go:
When he opened the valve, the balloon collapsed. Hundreds of buildings collapsed in the earthquake.
2 fail, (come to an) end, fall through, peter out, disintegrate, dissolve, fall flat, founder, come to naught or nought, break up or down; decline, diminish; disappear, evaporate, go up in smoke, go bankrupt, go under, Brit go to the wall, Colloq fizzle out:
After the imprisonment of their leader, the entire movement collapsed. Owing to the recession, many businesses collapsed.
3 pass out, faint, drop, Colloq keel over; Old-fashioned or literary swoon:
He collapsed on-stage and they took him to his dressing-room.
4 break down (mentally), have a (nervous) breakdown, go to pieces, come or fall apart, Colloq crack up, US also crack:
She finally collapsed from overwork and is now in a sanatorium.
5 cave-in, breakdown:
The collapse of the house was attributed to termites.
6 failure, downfall, ruin; disappearance, disintegration, dissolution, bankruptcy:
Will he be able to survive the collapse of his financial empire?
7 (mental) breakdown, prostration, Colloq crack-up:
He suffered a mental collapse when his family was killed in a car crash.