'antisupernaturalistic' originates from the prefix 'anti-' (from Greek ἀντί, meaning 'against'), the word 'supernatural' (from Latin 'super' + 'natura'), and the suffix '-istic' (Greek/Latin adjective-forming suffix meaning 'pertaining to').

'supernatural' entered English via Middle English from Old French 'supernaturel' and Latin 'supernaturalis'; 'antisupernaturalistic' is a Modern English formation combining 'anti-' + 'supernatural' + '-istic' to denote opposition to supernatural explanations.

Initially the elements meant 'against' + 'beyond nature'; combined as 'antisupernaturalistic' the word has meant from its formation to modern use essentially the same: expressing opposition to supernatural explanations, especially in favor of naturalistic accounts.