late 14c., "a message from a god expressed by divine inspiration through a priest or priestess," in answer to a human inquiry, usually respecting some future event, from Old French oracle "temple, house of prayer; oracle" (12c.) and directly from Latin oraculum, oraclum "divine announcement, oracle; place where oracles are given," from ōrare "to pray to, plead to, beseech" (see orator), with material instrumental suffix -culo-.
In antiquity, "the agency or medium of a god," also "the place where such divine utterances were given." This last sense is attested in English from early 15c. Extended sense of "uncommonly wise person" is from 1590s.
word-formation element meaning "pertaining to, of the nature of," from Latin -arem, -aris "of the kind of, belonging to," a secondary form (by dissimilation) of -alis, used after syllables with an -l- (such as insularis for *insulalis, stellaris for *stellalis).
<a href="https://www.etymonline.com/word/oracular">Etymology of oracular by etymonline</a>
Harper, D. (n.d.). Etymology of oracular. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/oracular