Lexical Definition

‎κῆτος‎ kētos (kay'-tos) sea monster G:N-N
probably from the base of ‎χάσμα‎

whale.

Usage: 4 forms in 8 verses
Form Translated As     In Verse(s)
κήτουσ great fish Matt.12.40
whale LXX.Jonah.1.17LXX.Jonah.2.1
κήτοσ whale LXX.Job.26.12
κήτη whales LXX.Gen.1.21LXX.Job.9.13
κήτει whale LXX.Jonah.1.17LXX.Jonah.2.10

Abbott-Smith

κῆτος, -εος (-ους), τό, [in LXX: Jh 2:1*, 11* (דָּג), Ge 1:21 (תַּנִּין), etc.;]
a huge fish, sea-monster: Mt 12:40(LXX).†

Abbott-Smith References

Book Refs
Genesis 1:21
Jonah 2:1* · 2:11*
Matthew 12:40

Liddell-Scott-Jones

κῆτος, εος, τό,

any sea-monster or huge fish, δελφῖνάς τε κύνας τε καὶ εἴ ποθι μεῖζον ἑλῃσι κῆτος [Refs 8th c.BC+]; of seals, [Refs 8th c.BC+]; of the monster to which Andromeda was exposed, [Refs 5th c.BC+]; of the tunny, [Refs 4th c.BC+]

__2 in Natural History, of the spouting cetacea, [Refs 4th c.BC+]
__II name of a constellation, [Refs 4th c.BC+]