Abbott-Smith Manual Greek Lexicon
Ἁρμαγεδών (G717)
1 Ἁρμαγεδών (WH, Ἃρ Μαγεδών ; Rec. Ἀρμαγεδδών , prop. = הַר מְגִדּוֹ ), cf. LXX, Μαγεδών , II Ch 35:22 , Μαγεδώ , Jg 1:27 ; Har-Magedon (AV, Armageddon ): Re 16:16 (v. Swete, in l., but also Thayer, s.v.).†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain