vig•i•lan•tePronunciation: (vij"u-lan'tē), [key]
a member of a vigilance committee.
any person who takes the law into his or her own hands, as by avenging a crime.
done violently and summarily, without recourse to lawful procedures: vigilante justice.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.