'rebaptizer' originates from the English prefix 're-' (from Latin 're-' meaning 'again') combined with the verb 'baptize', which ultimately comes from Greek 'baptizein', where the root 'bapto/bapt-' meant 'to dip'.

'baptize' entered English via Old French/Latin (Late Latin 'baptizare') from Greek 'baptizein'; the English formation 'rebaptize' (re- + baptize) produced the agent noun 'rebaptizer', and the plural form became 'rebaptizers'.

Originally the Greek root meant 'to dip' (physically); it evolved to mean 'to perform baptism' in Christian usage, and 'rebaptizer' specifically denotes one who performs or advocates baptism again ('to baptize again').