To rue something means to feel regret or sorrow about it, wishing you had made a different choice. When you rue a decision, you look back and think, “I really wish I hadn't done that.”

The word carries a heavy feeling of disappointment in yourself. A student who skipped studying might rue that choice when facing a difficult test. A soccer player might rue the moment they lost focus and let in the winning goal. The regret goes deeper than a passing “oops.” It's a persistent wish that you could go back and change what happened.

You'll often see rue paired with “the day,” as in “You'll rue the day you crossed me!” This dramatic phrase appears in stories when a villain warns someone they'll regret their actions. While it sounds old-fashioned and theatrical, it captures rue's meaning perfectly: a lasting regret about a specific moment or choice.