noun
(now chiefly historical) A search for people believed to be using sorcery or harmful magic, typically in order to persecute or punish them.
(by extension) An attempt to find and punish or harass a group of people perceived as a threat, usually on ideological or political grounds.
(by extension) A public or political campaign or investigation which smears a person or group.
verb
(informal) To perform a witch-hunt.