'antianxiety' originates from the combination of the prefix 'anti-' (from Greek 'anti' meaning 'against') and the noun 'anxiety' (from Latin 'anxietas').

'anxiety' entered English via Latin 'anxietas' (and Old French 'anxieté') into Middle English as 'anxiety'; the prefix 'anti-' comes from Greek 'anti' and was adopted into English as a productive combining form, giving rise to compounds like 'anti-anxiety' in modern usage.

Initially the parts meant 'against' + 'anxiety' (i.e., opposing anxiety); over time the compound came to be used chiefly to describe agents, medications, or measures that reduce or prevent anxiety and occasionally as a noun meaning 'an anxiolytic'.