'antiexpansionist' originates from Modern English, specifically the prefix 'anti-' (from Greek 'anti-' via Latin and French) meaning 'against', combined with 'expansionist', which derives from Latin 'expansio/expandere' where 'ex-' meant 'out' and the root (from Latin 'pandere') meant 'to spread'.

'antiexpansionist' is formed by joining 'anti-' and 'expansionist'. 'Expansion' comes from Latin 'expandere' → Old French (espand-) → Middle English 'expand', and the agentive/adjectival suffix '-ist' was added in modern English to form 'expansionist' (19th century); 'anti-' was then prefixed in Modern English to indicate opposition.

Initially, the components meant 'against' + 'those who favor expansion'; over time the compounded term has retained this core meaning of opposition to expansionism and is used to describe people, policies, or positions opposing expansion.