'paedobaptist' originates from Greek, specifically the words 'pais' (παῖς) and 'baptizein' (βαπτίζειν), where 'pais' meant 'child' and 'baptizein' meant 'to dip' or 'to baptize'.

'paedobaptist' developed in English by combining the prefix 'paedo-' (from Greek via New Latin) with 'baptist' (from Greek 'baptistes' and 'baptizein'); the term appears in English theological literature particularly during 17th-century debates over infant baptism and has remained in use since then.

Initially it meant 'one who baptizes children' or simply 'person who practices child baptism'; over time it has retained that sense and is now used to denote a supporter or practitioner of infant baptism.