Abbott-Smith Manual Greek Lexicon
σιδήρεος (G4603)
5 σιδήρεος , -α, -ον (-οῦς, -ᾶ -οῦν) ( σίδηρος ), [in LXX chiefly for בַּרְזֶל ;] of iron : Ac 12:10 , Re 2:27 9:9 12:5 19:15 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain