1. To retaliate, to punish someone in order to get even with someone else or to hit back with the intention of achieving justice: Sam avenged his mother's injury by the careless driver by reporting him to the police.

Bill planned to avenge his brother's death by setting the murderer's house on fire.

The settlers avenged the burning of the fort by destroying an Indian village.

2. Etymology: from Old French avengier, from a-, "to" + vengier, "to take revenge", accusative of vis dicta, literally "announced force"; that is, "announcement of force"; from Latin vindicare, "to claim, to avenge, to punish"; from vim dicare, "to show authority", from vim, accusative of vis, "force" + root of dicere, "to say".