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1894, from anti- + venin, from venom + chemical suffix -in (2). Perhaps immediately from French antivenin.
antivenin an·ti·ven·in (ān'tē-věn'ĭn, ān'tī-)n. An antitoxin active against venom.
An antitoxin active against the venom of a snake, spider, or other venomous animal or insect.
An animal serum containing antivenins, used in medicine to treat poisoning caused by animal or insect venom.