(yrʹə-nəs, y-rāʹnəs) noun. 1. Greek Mythology. The earliest supreme god, a personification of the sky, who was the son and consort of Gaea and the father of the Cyclopes and Titans. 2. The seventh planet from the sun, revolving about it every 84.07 years at a distance of approximately 2,869 million kilometers (1,790 million miles), having a mean equatorial diameter of 52,290 kilometers (32,480 miles) and a mass 14.6 times that of Earth, Uranus.