rue /ɹuː/verb 5noun 3forms 4phrases 1 verb5 •To repent of or regret (some past action or event); to wish that a past action or event had not taken place.I rued the day I crossed paths with her. •(no longer used) To feel sorrow or regret.Old year, we'll dearly rue for you. — 1832 •(no longer used) To feel compassion or pity; to take pity (on), to have compassion (on).[…] till our Lord's clouds rue upon the earth, and send down a watring of rain: Truly , I think Christ's misty dew a welcome message from heaven, till my Lord's rain fall : […] — 1724 •(no longer used) To cause to feel sorrow or pity. •(no longer used) To cause to repent of sin or regret some past action. noun3 •Any of various perennial shrubs of the genus Ruta, especially the herb Ruta graveolens (common rue), formerly used in medicines.But th'aged Nourse, her calling to her bowre, / Had gathered Rew, and Savine, and the flowre / Of Camphora, and Calamint, and Dill [...]. — 1590 •(dialect, no longer used) Sorrow; repentance; regret. •(dialect, no longer used) Pity; compassion. formsrued · rueing · ruing · rues Phrases with rue rue the dayTo seriously regret one's actions.