'anti-expansionism' originates from a modern English compound: the prefix 'anti-' (from Greek 'anti-' meaning 'against') + 'expansion' (from Latin 'expansio' via French/Latin forms) + the suffix '-ism' (from Greek '-ismos' via Latin '-ismus' meaning 'practice, system, or ideology').

'expand' comes from Latin 'expandere' ('ex-' meaning 'out' + 'pandere' meaning 'to spread'), which led to Late Latin 'expansio' and then English 'expansion'; combining this with the prefix 'anti-' and suffix '-ism' formed the modern compound 'anti-expansionism'.

Initially formed to mean 'opposition to expansion,' the term has retained that core sense and is used to describe a policy or ideology opposing territorial or political expansion.