—v.i. 1. to fall or cave in; crumble suddenly: The roof collapsed and buried the crowd. 2. to be made so that sections or parts can be folded up, as for convenient storage: This bridge table collapses. 3. to break down; come to nothing; fail: Despite all their efforts the peace talks collapsed. 4. to fall unconscious or as if unconscious or physically depleted, as from a stroke, heart attack, disease, or exhaustion.
5. Pathol. a. to sink into extreme weakness.
b. (of lungs) to come into an airless state.
—v.t. to cause to collapse: He collapsed the table easily.
—n. 1. a falling in or together: Three miners were trapped by the collapse of the tunnel roof. 2. a sudden, complete failure; breakdown: The bribery scandal brought about the complete collapse of his industrial empire.