To unfreeze means to thaw something that has been frozen, changing it from solid ice back to liquid or its normal state. When you take frozen peas out of the freezer and leave them on the counter, they gradually unfreeze and become soft again. A lake that froze solid during winter will unfreeze when spring warmth returns.

The word also means to release something that has been stopped or held in place. A computer program might freeze when it stops responding, and you have to restart it to unfreeze it. Banks can freeze someone's account so no money can move in or out, and then later unfreeze it to allow normal transactions again. A government might freeze spending on new projects during a budget crisis, then unfreeze that spending when finances improve.

Sometimes people use unfreeze playfully, like in the game of freeze tag, when someone gets tagged and must stand completely still, frozen in place, until another player runs over to unfreeze them with a touch.