<p><strong>Verb</strong></p><ul><li>(used without object)<ul><li>col·lapsed, col·laps·ing.</li><li>to fall or cave in; crumble suddenly: The roof collapsed and buried the crowd.</li><li>to be made so that sections or parts can be folded up, as for convenient storage: This bridge table collapses.</li><li>to break down; come to nothing; fail: Despite all their efforts, the peace talks collapsed.</li><li>to fall unconscious or as if unconscious or physically depleted, as from a stroke, heart attack, disease, or exhaustion.</li><li>Pathology: to sink into extreme weakness.</li><li>(of lungs) to come into an airless state.</li></ul></li></ul><p><strong>Noun</strong></p><ul><li>a falling in or together: Three miners were trapped by the collapse of the tunnel roof.</li><li>a sudden, complete failure; breakdown: The bribery scandal brought about the complete collapse of his industrial empire.</li></ul>