PRUSIAS, a town of Bithynia, anciently called Cior, from a cognominal river, and giving name to the Sinus Cianus of the Propontis; rebuilt by Prusias the son of Zela, after having been destroyed by Philip the son of Demetrius: it stood on the Sinus Cianus, at the foot of mount Arganthonius. This is the Prusias who harboured Annibal after the defeat of Antiochus.—Of this place was Afelepiades, furnished Prufeus, the famous physician.