vigilante(redirected from vigilanteism)
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n. someone who takes the law into his/her own hands by trying and/or punishing another person without any legal authority. In the 1800s groups of vigilantes dispensed "frontier justice" by holding trials of accused horse-thieves, rustlers and shooters, and then promptly hanging the accused if "convicted." A mother who shoots the alleged molester of her child is a vigilante.