1. infliction of injury, harm, humiliation, or the like, on a person by another who has been harmed by that person; violent revenge: But have you the right to vengeance? 2. an act or opportunity of inflicting such trouble: to take one's vengeance. 3. the desire for revenge: a man full of vengeance. 4. Obs. hurt; injury. 5. Obs. curse; imprecation.

6. with a vengeance, a. with force or violence. b. greatly; extremely. c. to an unreasonable, excessive, or surprising degree: He attacked the job with a vengeance.

[1250–1300; ME < OF, equiv. to vengi(er) to avenge (see VENGE) + -ance -ANCE]

—Syn. 1. requital, retaliation. See revenge.

—Ant. 1. forgiveness.

(Random House Webster's Unabridged)