vigilante

noun

1. a member of a vigilance committee.
2. any person who takes the law into his or her own hands, as by avenging a crime.

adjective

3. done violently and summarily, without recourse to lawful procedures: vigilante justice.

noun

1. one of an organized group of citizens who take upon themselves the protection of their district, properties, etc
2. Also called: vigilance man US a member of a vigilance committee

n.

“member of a vigilance committee,” 1856, American English, from Spanish vigilante, literally “watchman,” from Latin vigilantem (see vigilance). Vigilant man in same sense is attested from 1824 in a Missouri context. Vigilance committees kept informal rough order on the frontier or in other places where official authority was imperfect.