Strong's Greek #3989 - πέλαγος, ους, τό pelagos (the deep)

depth, sea.

Of uncertain affinity; deep or open sea, i.e. The main -- depth, sea.

Strong's 3989: πέλαγος

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.), Matthew 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, Acts 27:5 (see examples from Greek authors in Passow, under the word πέλαγος, 1; (Liddell and Scott, under I.)).

Strong's Greek: 3989. πέλαγος (pelagos) — 2 Occurrences

Matthew 18:6 - N-DNS
GRK: ἐν τῷ πελάγει τῆς θαλάσσης
NAS: and to be drowned in the depth of the sea.
KJV: in the depth of the sea.
INT: in the depth of the sea

Acts 27:5 - N-ANS
GRK: τό τε πέλαγος τὸ κατὰ
NAS: When we had sailed through the sea along the coast
KJV: when we had sailed over the sea of
INT: the and moreover along