'antiemetic' originates from modern coinage in medical Latin/Neo-Latin, built from the prefix 'anti-' (from Greek 'anti-' meaning 'against') plus 'emetic' (from Greek 'emētikos', from 'emein' meaning 'to vomit').

'emetic' came into English via Latin 'emeticus' from Greek 'emētikos' (related to the verb 'emein' 'to vomit'); the compound 'antiemetic' was formed in modern medical usage by combining 'anti-' + 'emetic' and adopted into English in the 19th century to name agents that oppose vomiting.

Initially formed to mean 'against vomiting' in a literal sense; it has retained that core sense and is now used both as an adjective describing a property and as a noun meaning a drug or agent that prevents vomiting.