The adjective sibylline means "having a secret meaning" or "foretelling the future," like a fortune teller whose crystal ball reveals a sibylline message about what will happen.
If you can predict the meaning of the word sibylline, you may come from a family of psychics — or you may have a background in Greek mythology. The word has origins in the Greek word Sibulla, meaning "prophetess." Back in the times of the Greeks and Romans, a sibyl was a female oracle who delivered cryptic prophecies foretelling the future, often inspired by the deities. The adjective sibylline describes such talents or the messages they reveal.