From Longman Dictionary of Contemporary Englishwildcat strikeˌwildcat ˈstrike noun [countable] BELan occasion when workers suddenly stop working in order to protest about something, usually without the support of a trade union
Examples from the Corpus
wildcat strike• The closed shop and the wildcat strike have undermined the legitimacy of modern trade unionism.From Longman Business Dictionarywildcat strikeˌwildcat ˈstrikeHUMAN RESOURCES a strike in which workers suddenly stop working in order to protest about something, but which has not been approved by the union → strike 