a. [ L. sibyllinus. ] Pertaining to the sibyls; uttered, written, or composed by sibyls; like the productions of sibyls. [ 1913 Webster ]

Sibylline books. (a) (Rom. Antiq.) Books or documents of prophecies in verse concerning the fate of the Roman empire, said to have been purchased by Tarquin the Proud from a sibyl. (b) Certain Jewish and early Christian writings purporting to have been prophetic and of sibylline origin. They date from 100 b. c. to a. d. 500. [ 1913 Webster ]