n. & v.
n. 1 the tumbling down or falling in of a structure; folding up; giving way. 2 a sudden failure of a plan, undertaking, etc. 3 a physical or mental breakdown.
v. 1 a intr. undergo or experience a collapse. b tr. cause to collapse. 2 intr. colloq. lie or sit down and relax, esp. after prolonged effort (collapsed into a chair). 3 a intr. (of furniture etc.) be foldable into a small space. b tr. fold (furniture) in this way. collapsible adj. collapsibility n.
[ L collapsus past part. of collabi (as COM-, labi slip) ]