In Greek mythology. Circular stream that flows around the edge of theearth. The sun and moon rise from and descend into this stream; it is thesource of all rivers. 2Personification of the circular stream describedabove. He was the Titan son of Uranus and Gaea, the husband of Tethys,and the father of the river-gods and the sea nymphs (or oceanids). He wasconceived of as a powerful but kindly old man. Some legends say thatDione was also the daughter of Oceanus and Tethys.