'anti-paedobaptist' originates from Modern English as a compound of the prefix 'anti-' (from Greek anti, meaning 'against'), the combining form 'paedo-' (from Greek pais/paidos, meaning 'child'), and 'baptist' (from Greek baptizein, meaning 'to dip or immerse').

'anti-' and the combining form 'paedo-' entered English via Classical/Medieval Latin and later Modern English usage of Greek-derived scientific and theological prefixes; 'baptist' derives from Greek 'baptistēs' / 'baptizein', passed into Late Latin and Old French before becoming English 'baptist'. The full compound arose in post-Reformation theological debates (17th century onward) as English speakers combined these elements to describe opponents of infant baptism.

Initially the compound was used specifically to denote those opposed to infant (paedo-) baptism in theological contexts; over time it has retained that core sense and is still used chiefly in historical and theological discourse to mean 'a person opposed to paedobaptism.'