1. bitterly regret (something one has done or allowed to happen):"Ferguson will rue the day he turned down that offer"
noun
1. repentance; regret: archaic"with rue my heart is laden"
▪ compassion; pity:archaic"tears of pitying rue"
Word OriginOld Englishhrēow ‘repentance’, hrēowan ‘affect with contrition’, of Germanic origin; related to Dutch rouw ‘mourning’ and German Reue ‘remorse’.