Abbott-Smith Manual Greek Lexicon
Ἰσαάκ (G2464)
20 Ἰσαάκ (in MSS. sometimes -σάκ ; cf. Deiss., BS , 189; Thack., Gr. , 100), ὁ , indecl. (in FlJ, Ἴσακος, -ου ), (Heb. יִצְחָק ), Isaac ( Ge 17:19 , al.): Mt 1:2 , Ro 9:10 , al.
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain