πέλαγος, πελαγους, τό (by some (e. g. Lob. Pathol. Proleg., p. 805) connected with παξ, i. e. the ’flat’ expanse (cf. Latinaequor); but by Curtius, § 367, et al. (cf. Vanicek, p. 515) with πλήσσω, i. e. the ’beating’ waves (cf. our ’plash’)), from Homer down;

a. properly, the sea i. e. the high sea, the deep (where ships sail; accordingly but a part of the sea, θάλασσα, Aristotle, Probl. sect. 23 quaest. 3 (p. 931{b}, 14f) ἐν τῷ λιμενι ὀλίγη ἐστιν ἡ θάλασσα, ἐν δέ τῷ πελάγει βαθεῖα. Hence) τό πέλαγος τῆς θαλάσσης,aequor maris (A. V. the depth of the sea; cf. Trench, § xiii.), Mat 18:6 (so too Apollonius Rhodius, 2, 608; πέλαγος αἰγαιας ἁλός, Euripides, Tro. 88; Hesychius πέλαγος ... βυθός, πλάτος θαλάσσης. Cf. Winers Grammar, 611 (568); (Trench, as above)).

b. universally, the sea: τό πέλαγος τό κατά τήν Κιλικίαν, Act 27:5 (see examples from Greek authors in Passow, under the word πέλαγος, 1; (Liddell and Scott, under I.)).