'postbaptismal' is formed from Latin 'post' (origin language: Latin), specifically the word 'post', where 'post' meant 'after', combined with 'baptismal' which ultimately comes from Greek 'baptisma' (via Late Latin 'baptismus'), where the root 'baptein' meant 'to dip or immerse'.

'postbaptismal' arose by combining the Latin prefix 'post' with the noun 'baptism' (from Greek 'baptisma' → Late Latin 'baptismus' → Old/Middle English 'baptism'), producing the Modern English adjective 'post-baptismal' (later written without the hyphen as 'postbaptismal').

Initially it literally meant 'after baptism' (i.e., occurring after the act of baptism); over time it has been used more broadly as an adjective describing rites, periods, effects, or characteristics pertaining to the time following baptism.