οὐκ ἔστι σιγᾶν αἰσχρόν, ἀλλ' εἰκῆ λαλεῖν → keeping silence is not shameful; speaking at random is (Menander)
P. σπηλαῖον, τό (Plato), Ar. and V. ἄντρον, τό, αὔλιον, τό, V. θαλάμαι, αἱ, P. and V. σῆραγξ, ἡ (Plato, Phaedo. 110A and Soph., Fragment).
γλάφυ, γύαλον, κατῶρυξ, πέτρα, σπέος, σπήλαιον, σπῆλυγξ