Abbott-Smith Manual Greek Lexicon
Ω, ω, ὦ μέγα (G5598)
4 (KJV) Ω, ω, ὦ μέγα (cf. ὂ μικρόν ), omega , ô, the twenty-fourth and last letter. As a numeral, ωʹ = 800, ω͵ = 800,000. As a symbol of the last (= τὸ τέλος ), τὸ Ὦ (Rec. Ω , L, ὦ , T, ω ), the Omega : Re 1:8 21:6 22:13 (cf. Ἄλφα ).†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain