'exclusionary' originates from English, specifically the word 'exclusion' combined with the adjectival suffix '-ary', where the suffix '-ary' meant 'pertaining to' or 'relating to'.

'exclusion' ultimately comes from Latin 'excludere' (ex- 'out' + claudere 'to shut'). Late Latin gave 'exclusio' ('a shutting out'), which passed into Old/French and Middle English as 'exclusion' and later yielded the modern English adjective 'exclusionary' by adding '-ary'.

Initially rooted in the literal sense 'to shut out' (from Latin), the sense evolved into the adjectival meaning 'characterized by or tending to exclude' in modern English usage.