PEGASOS (Pegasus) was an immortal, winged horse which sprang from the neck of the beheaded Gorgon Medousa (Medusa). It was tamed by Bellerophon who rode it into battle against the fire-breathing monster known as the Khimaira (Chimera). Later the hero attempted to fly to heaven but Zeus caused the horse to buck throwing him back down to earth in disgrace. Pegasos winged his way on to Olympos where he became the thunderbolt-bearer of Zeus.
Pegasos was commemorated amongst the stars as the constellation of the same name. Its rising marks the arrival of spring and, in Greece, of seasonal thunderstorms.
Pegasos' name means either "of the spring" from the Greek word pêgê, or "sprung forth" from the word pêgazô. The first alludes to the steed's connection with various springs, and the latter to its birth from the Gorgon's neck.