The act of inflicting harm in return for an injury or wrong done to oneself or another.
It is the committing of an act of ‘getting even’ or ‘exacting a perceived justice’. It may be a legal act (justified by law), but it is not necessarily an act sanctioned-by or carried-out by a legal authority.
God used this word 17 times in Scripture; 15 times to Israel in the Old Testament, 2 times to the Body of Christ, and never to Israel in the tribulation.
See also Judgement, Justice, Vengeance