Abbott-Smith Manual Greek Lexicon
ὄγδοος (G3590)
5 ὄγδοος , -η, -ον , the eighth : Lk 1:59 , Ac 7:3 (LXX) , Re 17:11 21:20 ; one of eight , with seven others (usually, in this sense, with αὐτός added, but cf. Plat., Legg. , iii, 695c; Plut., Pelop. , 13; II Mac 5:27 ): II Pe 2:5 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain