Ruin means to destroy or severely damage something, making it no longer useful, beautiful, or functional. When you spill grape juice on your favorite white shirt and it won't come out, the stain ruins the shirt. When a sudden rainstorm ruins an outdoor birthday party, it makes the celebration impossible to continue as planned.

The word carries a sense of loss: something that was good or valuable becomes worthless or unusable. A careless moment can ruin months of careful work, like when someone accidentally deletes an entire project file. Bad decisions can ruin a friendship or ruin someone's reputation.

Ruin can also be a noun meaning the remains of something destroyed. Ancient ruins are the crumbled walls and broken columns left from civilizations long ago. The Roman Forum and Mayan temples stand in ruins today, giving us glimpses of vanished worlds. When something falls into ruin, it gradually decays through neglect.

The phrase in ruins describes complete destruction: “After the fire, the old library lay in ruins.” Sometimes people say someone is “ruined” financially when they've lost all their money, though people can usually rebuild their lives even after serious setbacks.