'rebaptise' originates from the Latin prefix 're-' meaning 'again' combined with 'baptise', which comes from Greek 'baptizein' meaning 'to dip'.

'baptize' comes from Greek 'baptizein' -> Late Latin 'baptizare' -> Old French/Medieval Latin forms -> Middle English 'baptysen'/'baptisen'; the modern English verb 'rebaptise' was formed by adding the Latin-derived prefix 're-' to 'baptise' (Early Modern English formation).

Initially related to 'to dip' (the literal Greek sense), it came to mean the Christian rite of 'to baptize', and 'rebaptise' developed to mean 'to baptize again' (and by extension, 'to give a new name').