If you rue the day that you did something, you are sorry that you did it, because it has had unpleasant results. You'll live to rue the day you said that to me, my girl. to wish that you had not done something = regret
If you rue something that you have done, you are sorry that you did it, because it has had unpleasant results. Tavare was probably ruing his decision. = regret
sadness associated with some wrong done or some disappointment; "he drank to drown his sorrows"; "he wrote a note expressing his regret"; "to his rue, the error cost him the game"
(French) a street or road in France leaves sometimes used for flavoring fruit or claret cup but should be used with great caution: can cause irritation like poison ivy European strong-scented perennial herb with gray-green bitter-tasting leaves; an irritant similar to poison ivy
If someone is rueful, they feel or express regret or sorrow in a quiet and gentle way. He shook his head and gave me a rueful smile + ruefully rue·ful·ly He grinned at her ruefully. feeling or showing that you wish you had not done something