/ ˌvɪdʒɪˈlænti; NAmE / noun
(sometimes disapproving ) a member of a group of people who try to prevent crime or punish criminals in their community, especially because they think the police are not doing this
► vigi·lant·ism / ˌvɪdʒɪˈlæntɪzəm; NAmE / noun [ U ]
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WORD ORIGIN
mid 19th cent.: from Spanish , literally vigilant .