'intoxicant' originates from Late Latin, specifically the verb 'intoxicare', where 'in-' meant 'in/into' and the element related to Latin/Greek 'toxicum'/'toxikon' meant 'poison'.

'intoxicare' passed into Medieval/Modern Latin and influenced Old French/English forms such as 'intoxicate' (verb); the English noun 'intoxicant' was formed by adding the agentive suffix '-ant' to the verb stem.

Initially related to 'poisoning' or 'toxic effect' (literally causing harm by a poisonous substance); over time the sense broadened to include causing drunkenness or strong exhilaration (physical or figurative).