A head of a family or tribe.

These were DUKES of the sons of Esau: the sons of Eliphaz the firstborn son of Esau; DUKE Teman, DUKE Omar, DUKE Zepho, DUKE Kenaz. ( Genesis 36:15 )

Source: A King James Dictionary. (Used with permission. Copyright © Philip P. Kapusta)

Bibliography Information

"Entry for 'Duke'". A King James Dictionary.