Definitions
1.AdjectiveOf or pertaining to or resembling a sibyl or female oracle, especially the Cumaean Sibyl and the Sibylline Books. .mw-parser-output .defdate{font-size:smaller}
2.AdjectiveHaving oracle-like predicting powers, clairvoyant.
3.AdjectiveOccult, mysterious.
4.AdjectiveExcessively and exorbitantly expensive. (In allusion to the Sibyl who sold three books to Tarquinius Superbus at the price of the original nine.)
5.NounOne of the Sibylline Oracles or Sibylline Books.