'antilegalist' originates from Modern English, specifically formed from the prefix 'anti-' (from Greek 'anti' meaning 'against') + 'legalist' (from 'legal' + suffix '-ist', where Latin 'lex/leg-' meant 'law').

'legal' derives from Latin 'legalis' (from 'lex, legis' meaning 'law'); 'legalist' arose in English to denote a proponent of legalism, and 'antilegalist' is a modern compound formed by adding the productive prefix 'anti-' to 'legalist'.

Initially components meant 'against' (anti-) and 'law' (lex/leg-); combined as 'antilegalist' the term has the current meaning 'one who opposes legalism' without substantial semantic shift from its parts.