Sibylline

sib·yl·line /ˈsɪbəˌlin, -ˌlaɪn, -lɪn/ Pronunciation Key - Show Spelled Pronunciation[sib-uh-leen, -lahyn, -lin] Pronunciation Key - Show IPA Pronunciation

–adjective

1.	of, resembling, or characteristic of a sibyl; prophetic; oracular.

2.	mysterious; cryptic.

Also, si·byl·ic, si·byl·lic