'racialist' originates from English, formed by the adjective 'racial' (from French/Italian roots of the word 'race') plus the agentive suffix '-ist', where 'racial' relates to 'race' and '-ist' denotes 'one who adheres to or practices'.

'racial' developed from the noun 'race' (from French 'race', ultimately from Italian 'razza'), which entered English in the modern period; the suffix '-ist' (from Greek/Latin via French) was added to create 'racialist'.

Initially, formations with '-ist' could indicate someone concerned with or studying races; over time 'racialist' has come to specifically describe someone who advocates racial hierarchy or discrimination.