To collapse means to fall down or cave in suddenly, usually from weakness or loss of support. When an old barn collapses, its roof caves in and its walls crumble to the ground. A tunnel might collapse if the earth around it shifts. A bridge collapses when its structure fails and it falls into the river below.

People can collapse too. An exhausted marathon runner might collapse at the finish line, their legs giving out beneath them. Someone who faints collapses to the floor. The word captures that sudden loss of strength: one moment you're standing, the next you've fallen.

Organizations and systems can also collapse. When a business collapses, it fails completely and shuts down. An empire collapses when it loses power and falls apart. If your carefully built house of cards collapses, it means all your delicate work has tumbled down in an instant.

The word suggests something more dramatic than just falling. Collapse implies that whatever fell couldn't hold itself up anymore, whether from exhaustion, damage, or structural weakness. It's the moment when something that was standing, functioning, or holding together simply can't anymore.