'antiaggressionist' originates from the prefix 'anti-' (from Greek 'anti' meaning 'against'), the noun 'aggression' (from Latin 'aggressio'), and the English suffix '-ist' meaning 'one who'.

'aggression' comes from Latin 'aggredi/ aggressio' (to approach, attack) and passed into Old French and Middle English as 'aggression'; 'anti-' entered English from Greek via Latin/Old French; the agentive suffix '-ist' comes into English via French and Latin. The compound 'antiaggressionist' is a modern English formation combining these elements.

Initially the components referred literally to 'against attack' (anti- + aggression). Over time the compound has come to denote specifically 'a person who opposes aggressive actions or policies,' including political or ethical stances against aggression.