Quick Definition
666
Strong's Definition
666 as a numeral
Derivation: the 22nd, 14th and an obsolete letter (G4742 (στίγμα) as a cross) of the Greek alphabet (intermediate between the 5th and 6th), used as numbers; denoting respectively 600, 60 and 6;
KJV Usage: six hundred threescore and six
Thayer's Greek Lexicon
χξς, six hundred and sixty-six (chi Χ = 600; xi Ξ = 60; sigma ς' = 6), a mystical number the meaning of which is clear when it is written in Hebrew letters, χρψ πψεο, i. e. Νέρων Καῖσαρ, 'Nero Caesar' (sometimes the Jews write χρψ for the more common χιρψ, the Syriac always rSK [], cf. Ewald, Die Johann. Schriften, ii., p. 263 note; (Schürer, N. T. Zeitgesch. edition 1, § 25 III., p. 449 note); π (nun) = 50, ψ (resh) = 200, ε (waw) = 6, π (nun) = 50, χ (qoph = 100, ρ (camek) = 60, ψ (resh) = 200): Rev_13:18 R G T Tr. (For a digest of opinions respecting this much debated number see Lee in the 'Speaker's commentary' at the passage.)
Mounce Concise Greek Dictionary
not given
Abbott-Smith Greek Lexicon
χξς´
(on ς , see Z ), in T , Tr ., Rec. for ἑξακόσιοι ἑξήκοντα ἕξ , six hundred and sixty-six (L, mg ., R , mg ., six hundred and sixteen ), the mystical number of the Beast: Rev_13:18 (on the interpretation, v. Swete , Ap., 172 f .).†
STEPBible — Tyndale Abridged Greek Lexicon
χξς ́
(on ς, see: Z), in T, Tr., Rec. for ἑξακόσιοι ἑξήκοντα ἕξ,
six hundred and sixty-six (L, mg., R, mg., six hundred and sixteen), the mystical number of the Beast: Rev.13:18 (on the interpretation, see Swete, Ap., 172 f.).†
(AS)