'divinatory' originates from Latin, specifically the verb 'divinare' and the adjective-forming element (from Latin 'divinatorius'), where 'divinare' meant 'to foresee' or 'to prophesy' and 'divinus' meant 'divine'.

'divinatory' changed from the Latin adjective 'divinatorius' (and related Medieval/Anglo-French forms such as 'divinatoire') and eventually entered English as 'divinatory' in the sense of relating to divination.

Initially it was connected to 'divine' or matters 'of a god' (and to acts of seeking knowledge from the divine); over time it came to be used specifically for things 'relating to divination' or 'serving to foretell'.