sibylline

[ sib-uh-leen, -lahyn, -lin ]

/ ˈsɪb əˌlin, -ˌlaɪn, -lɪn /

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

mysterious; cryptic.

Also si·byl·ic, si·byl·lic

[si-bil-ik] /sɪˈbɪl ɪk/.

Origin of sibylline

First recorded in 1570–80, sibylline is from the Latin word Sibyllīnus pertaining to a sibyl. See sibyl, -ine¹