'exclusionism' originates from Latin, specifically the verb 'excludere' where the prefix 'ex-' meant 'out of' and 'cludere/claudere' meant 'to close'; the English noun 'exclusion' + the suffix '-ism' produced 'exclusionism'.

'Exclusionism' developed in English by combining the noun 'exclusion' (from Latin 'exclusio' / Old French forms) with the ideological/formal suffix '-ism', forming a term used to denote a doctrine or policy of exclusion.

Initially related simply to the act or state of excluding ('the fact of being excluded'), it came to be used more often for an ideological or policy stance: 'a doctrine or practice favoring exclusion'.