When ice, snow, or something else that is frozen thaws, it melts.

A thaw is a period of warmer weather when snow and ice melt, usually at the end of winter.

When you thaw frozen food or when it thaws, you leave it in a place where it can reach room temperature so that it is ready for use.

If something thaws relations between people or if relations thaw, they become friendly again after a period of being unfriendly.