Dictionary entry

κλείς

G. Abbott-Smith's A Manual Greek Lexicon of the New Testament

κλείς, -δός, Att.. acc., κλεῖν, later -εῖδα, pl., κλεῖδες, -ας, contr., -εῖς, ἡ,

[in LXX for מַפְתֵּחַ, Is 22:22, al.;]

a key. Fig., τ. βασιλείας τ. οὐρανῶν, Mt 16:19; τ. γνώσεως, Lk 11:52; of David (cf. LXX, Is 22:22), Re 3:7; τ. θανάτου κ. τ. ᾅδου, Re 1:18; τ. ἀβύσσου, Re 20:1; τ. φρέατος τῆς ἀ., Re 9:1.†