Any member of the genus Glaucus of nudibranchiate mollusks, found in the warmer latitudes, swimming in the open sea, strikingly colored with blue and silvery white.

(Greek mythology) A Greek prophetic sea-god, born mortal and turned immortal upon eating a magical herb. It was believed that he commonly came to the rescue of sailors and fishermen in storms, having once been one himself.

plural of glaucus