I.a rock, a ledge or shelf of rock, Od.
2.a rock, i. e. a rocky peak or ridge, Hom.; π. σύνδρομοι, ξυμπληγάδες, of the rocky islets of the Bosporus, Pind., Eur.; π. δίλοφος, of Parnassus, Soph.—Properly, πέτρα is a fixed rock, πέτρος a stone: in Od. 9, πέτραι are masses of live rock torn up by giants.