'exorcistic' originates from Medieval Latin, specifically the word 'exorcisticus', where 'exorc-' ultimately comes from Greek 'exorkizein' (ἐξορκίζειν) meaning 'to bind by oath/adjure' and the suffix '-isticus' meant 'pertaining to'.

'exorcistic' changed from Late/Medieval Latin 'exorcisticus' (derived from Latin 'exorcismus' from Greek 'exorkizein') and entered English via Medieval/early modern Latin and borrowings in religious contexts, eventually becoming the modern English adjective 'exorcistic'.

Initially it was used in religious and liturgical contexts to mean 'pertaining to rites for expelling spirits'; over time it has kept that core sense and is now used more generally to describe anything reminiscent of or related to exorcism.