From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

KENIZZITES . A clan named from an eponymous ancestor, Kenaz . According to J [Note: Jahwist.] (  Joshua 15:17 ,   Judges 1:13 ), Caleb and Othniel were descended from him. (The Inference, sometimes made, that Kenaz was a brother of Caleb, arose from a misunderstanding of these passages.) R [Note: Redactor.] in   Joshua 14:6;   Joshua 14:14 definitely calls Caleb a Kenizzite, as P [Note: Priestly Narrative.] does in   Numbers 32:12 . R [Note: Redactor.] also (  Genesis 15:18-21 ) counts the Kenizzites among the pre-Israelitish inhabitants of Palestine. P [Note: Priestly Narrative.] in   Genesis 36:42 enrols Kenaz among the ‘dukes’ of Edom, while a Priestly supplementer counts him both as a ‘duke’ and as a grandson of Esau (  Genesis 36:11;   Genesis 36:16 ). The Chronicler names Kenaz as a grandson of Esau (  1 Chronicles 1:36 ), and also as a descendant of Judah (  1 Chronicles 4:13-15 ). The probable meaning of all these passages is that the Kenizzites overspread a part of Edom and southern Judah before the Israelitish conquest and continued to abide there, a part of them being absorbed by the Edomites, and a part by the tribe of Judah. This latter portion embraced the clans of Caleb and Othniel.

George A. Barton.

American Tract Society Bible Dictionary [2]

An ancient people of Canaan, whose land God promised to the descendants of Abraham,  Genesis 15:19 . They appear to have mingled with other Canaanites, and lost their distinctive name before the time of Joshua. They should be distinguished from the Kenezites, the children of Kenaz. Two men so named are mentioned in Bible history, both subsequent to the Kenizzites,  Genesis 36:15,42;  Joshua 14:6;  15:17 .

Watson's Biblical & Theological Dictionary [3]

an ancient people of Canaan, whose land God promised to the descendants of Abraham,  Genesis 15:19 . It is thought that this people dwelt in the mountains south of Judea.

Morrish Bible Dictionary [4]

Mentioned only once as people in the land promised to Abraham.  Genesis 15:19 .

Kitto's Popular Cyclopedia of Biblial Literature [5]

Ken´izzites, a Canaanitish tribe, mentioned in , along with others, over which it was promised that the seed of Abraham should have dominion. The notion that they sprung from Kenaz, the grandson of Edom, and had their dwelling somewhere in Idumea, cannot be entertained, seeing that the tribe is named long before Kenaz had existence. The Kenizzites of; , appear, however, to be a different race, the origin of which may without improbability be ascribed to Kenaz. The Kenizzites are not named among the nations whom the Israelites eventually subdued; whence it may be supposed that they had by that time merged into some of the other nations which Israel overcame.