|Origin:||collapsus, past participle of collabi, from com- ( COM-) + labi 'to fall, slide'|
if a building, wall etc collapses, it falls down suddenly, usually because it is weak or damaged:
Uncle Ted's chair collapsed under his weight.
The roof had collapsed long ago.
to suddenly fall down or become unconscious because you are ill or weak:
He collapsed with a heart attack while he was dancing.
Marion's legs collapsed under her.
if a system, idea, or organization collapses, it suddenly fails or becomes too weak to continue:
The luxury car market has collapsed.
I thought that without me the whole project would collapse.
if prices, levels, etc collapse, they suddenly become much lower:
There were fears that property prices would collapse.
to suddenly sit down, especially because you are very tired or want to relax:
I was so exhausted when I got home, I just collapsed on the sofa.
if a piece of furniture or equipment collapses, or if you collapse it, you can fold it so that it becomes smaller:
fold something smaller[intransitive and transitive]
The legs on our card table collapse so we can store it in the closet.
if a lung or a blood vessel collapses, it suddenly becomes flat, so that it no longer has any air or blood in it