(of a structure) suddenly fall down or give way

the roof collapsed on top of me

(of a person) fall down and become unconscious as a result of illness or injury

he collapsed from loss of blood

fail suddenly and completely

the talks collapsed last week over territorial issues

fold or be foldable into a small space

some cots collapse down to fit into a holdall

an instance of a structure falling down or giving way

the collapse of a railway bridge

the church roof is in danger of collapse