To fall down or give way suddenly, typically as a result of structural failure. The old building collapsed after the earthquake.
To fold or be folded into a more compact form. She collapsed the stroller and put it in the trunk of the car.
To suddenly lose force, significance, or effectiveness. The negotiations collapsed after the two sides failed to reach an agreement.
To break down in health or strength; to suffer a physical or mental breakdown. He collapsed from exhaustion after running the marathon.
To cause something to fall or cave in. The workers collapsed the old bridge to make way for a new one.