rue

Sorrow; repentance; regret.

When I was one-and-twenty I heard him say again, / "The heart out of the bosom was never given in vain; / 'Tis paid with sighs aplenty and sold for endless rue." / And I am two-and-twenty, and oh, 'tis true, 'tis true.

Pity; compassion.

To repent of or regret (some past action or event); to wish that a past action or event had not taken place.

to rue the day

I rued the day I crossed paths with her.

To cause to repent of sin or regret some past action.

To cause to feel sorrow or pity.

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 : […]

1842, Nicholas Ridley, The Life of Nicholas Ridley which stirred men's hearts to rue upon them

To feel sorrow or regret.

Old year, we'll dearly rue for you.

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 [...].

Ophelia: There’s fennel for you, and columbines: there’s rue for you; and here’s some for me: we may call it herb-grace o' Sundays: O you must wear your rue with a difference.