sib·yl (s?b??l)n.1. One of a number of women regarded as oracles or prophets by the ancient Greeks and Romans.2. A woman prophet.[Middle English sibile, from Old French, from Latin Sibylla, from Greek Sibulla.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.sibyl (?s?b?l) n1. (Classical Myth & Legend) (in ancient Greece and Rome) any of a number of women believed to be oracles or prophetesses, one of the most famous being the sibyl of Cumae, who guided Aeneas through the underworld2. (Alternative Belief Systems) a witch, fortune-teller, or sorceress[C13: ultimately from Greek Sibulla, of obscure origin] sibylline sibyllic, sibylic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014sib?yl (?s?b ?l) n. 1. any of a group of semilegendary women of the ancient world, who possessed prophetic powers. 2. a female prophet or fortune-teller. [1250?1300; Middle English Sibil