'antiaggressive' is a modern English compound formed from the combining prefix 'anti-' (from Greek 'anti' meaning 'against') and the adjective 'aggressive' (from Latin-based 'aggress-').

'aggressive' comes from Latin 'aggredi' (to approach, attack), via Late Latin/Old French developments into English as 'aggressive'; the prefix 'anti-' has been used in English since Classical borrowings to form compounds meaning 'against'. The compound 'antiaggressive' is a contemporary formation combining these elements.

Initially, elements like 'aggredi' meant 'to step toward' or 'attack'; over time 'aggressive' came to mean 'hostile' or 'assertive'. 'Antiaggressive' therefore developed as a negation meaning 'against aggression' or 'non-aggressive'.