πέτρα
Alt. πέτρα, ionic and epicπέτρη, ἡ,
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.
3. πέτρη γλαφυρή a hollow "rock", i. e. a cave, Il.; δίστομος π. "a cave in the rock" with a double entrance, Soph.
II. proverbial usages:—on οὐκ ἀπὸ δρυὸς οὐδ᾽ ἀπὸ πέτρης, v. δρῦς:— as a symbol of firmness, ὁ δ᾽ ἐστάθη ἠύτε πέτρη Od.; of hardheartedness, ἐκ πέτρας εἰργασμένος Aesch.