'baptizer' originates from Greek, specifically the verb 'baptizein', where the root 'bapto/bapt-' meant 'to dip, to immerse'.

'baptizein' (Greek) passed into Late Latin as 'baptizare', then into Old French as 'baptiser', and later into Middle English leading to the modern English 'baptize' and the agent noun 'baptizer'.

Initially it meant 'to dip or immerse'; over time it became specialized to mean 'to perform the sacrament of baptism', and 'baptizer' came to mean 'one who performs that rite'.