Ἰουδαῖος: a Jew

Ἰουδαῖος Judæan, i.e. belonging to Jehudah
Derivation: from G2448 (in the sense of G2455 as a country);
KJV Usage: Jew(-ess), of Judæa. G2448 G2455

Thayer:

1) Jewish, belonging to the Jewish nation
2) Jewish as respects to birth, origin, religion

Ἰουδαῖος
Ioudaios
ee-oo-dah'-yos
From G2448 (in the sense of G2455 as a country); udaean, that is, belonging to Jehudah
KJV Usage: Jew (-ess), of Juda.