sibylline
/ˈsɪbɪlaɪn/adj
High School
1
Of or pertaining to or resembling a sibyl or female oracle, especially the Cumaean Sibyl and the Sibylline Books.
2
Having oracle-like predicting powers, clairvoyant.
3
Occult, mysterious.
4
Excessively and exorbitantly expensive. (In allusion to the Sibyl who sold three books to Tarquinius Superbus at the price of the original nine.)