JEW - A Jehudite, i.e., descendant of Judah; a name formed from that of the patriarch Judah and applied first to the tribe or country of Judah or to a subject of the kingdom of Judah (2 Kings 25:25; Jer 32:12; 38:19; 40:11; 41:3; 52:28) in distinction from the seceding ten tribes, the Israelites.

From the time of the Babylonian captivity, as the members of the tribe of Judah formed by far the larger portion of the remnant of the covenant people, Jews became the appellation of the whole nation (2 Macc. 9:17; John 4:9; 7:1; Acts 18:2,24).

The original designation of the Israelite people was the Hebrews, as the descendants of Abraham. Thus Paul was appropriately called a Hebrew, and still later the terms Hebrew and Jew were applied with little distinction.

(from The New Unger's Bible Dictionary. Originally published by Moody Press of Chicago, Illinois. Copyright © 1988.)