resembling or characteristic of a prophet or prophecy; "the high priest's divinatory pronouncement"; "mantic powers"; "a kind of sibylline book with ready and infallible answers to questions"

having a secret or hidden meaning; "cabalistic symbols engraved in stone"; "cryptic writings"; "thoroughly sibylline in most of his pronouncements"- John Gunther

Pertaining to the sibyls; uttered, written, or composed by sibyls; like the productions of sibyls.