'non-Baptist' is formed from the prefix 'non-' (from Latin 'non', meaning 'not') attached to 'Baptist'. 'Baptist' comes from Greek 'baptizein' via Late Latin/Medieval Latin 'baptista', meaning 'one who baptizes' or a follower of a baptizing movement.

'Baptist' is derived from Greek 'baptizein' which passed into Late Latin/Medieval Latin as 'baptista' and into English as 'Baptist' (denoting followers of the 17th-century Baptist movement). The modern compound 'non-Baptist' arose by adding the negative prefix 'non-' to denote absence of that affiliation.

Initially, 'Baptist' denoted someone who baptizes or a member of the Baptist movement; 'non-Baptist' has meant 'not of the Baptist denomination' since its formation and has retained that basic sense.