bright star in the constellation Canis Minor (the 8th brightest in the sky), 1650s, from Latin, from Greek Prokyōn, the name of the star or the constellation (which has few other visible stars), from pro "before" (see pro-) + kyōn "dog" (from PIE root *kwon- "dog"). So called from its rising just before the "Dog Star," Sirius.
By Roman astronomers, sometimes Latinized as Antecanis. A mid-15c. English Prochion seems to refer to the constellation.