'anti-separation' is a modern English compound formed from the prefix 'anti-' (from Greek 'anti-' meaning 'against') + 'separation' (from Latin 'separatio').

'anti-' originates from Greek 'anti' meaning 'against'; 'separation' comes from Latin 'separatio' (from 'separare' meaning 'to separate') and entered English via Old French/Latin developments. The hyphenated compound 'anti-separation' is a productive modern English formation combining these elements.

Initially, the elements meant 'against' + 'the act of separating'; over time the compound has come to denote a position, policy, or descriptive adjective opposing separation in specific political, social, or organizational contexts.