To avenge means to punish someone who has harmed you or someone you care about, seeking justice for a wrong that was done. When a character in a story vows to avenge their fallen friend, they're promising to make the wrongdoer pay for what they did.

Avenge is different from simple revenge. Avenging suggests righting a wrong or restoring balance, often with a sense of justice behind it. In The Count of Monte Cristo, Edmond Dantès spends years planning how to avenge his wrongful imprisonment. In superhero stories, heroes often fight to avenge innocent victims.

An avenger is someone who carries out this justice. You might read about someone avenging a defeat by training hard and winning a rematch, or a team avenging last year's championship loss by coming back stronger and winning this year.