Peg·a·sus (p?g??-s?s)n.1. Greek Mythology A winged horse that with a stroke of his hoof caused the fountain Hippocrene to spring forth from Mount Helicon.2. A constellation in the Northern Hemisphere near Aquarius and Andromeda.[Middle English, from Latin P?gasus, from Greek P?gasos.]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.Pegasus (?p???s?s) n (Classical Myth & Legend) Greek myth an immortal winged horse, which sprang from the blood of the slain Medusa and enabled Bellerophon to achieve many great deeds as his riderPegasus (?p???s?s) n, Latin genitive Pegasi (?p????sa?) (Celestial Objects) a constellation in the N hemisphere lying close to Andromeda and PiscesCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Peg?a?sus (?p?g ? s?s) n. gen. -si (-?sa?) for 2. 1. a winged horse of Greek myth. 2. the Winged Horse, a northern constellation between Cygnus and Aquarius. Pe?ga?si?an (p??ge? si ?n) adj. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.Peg·a·sus (p?g??-s?s) A constellation in the Northern Hemisphere near Aquarius and Andromeda.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.