WAS KETURAH THE WIFE, OR THE CONCUBINE, OF ABRAHAM?

Genesis 25:1-2  Then again Abraham took a wife, and her name was Keturah. (KJV)  And she bare him Zimran, and Jokshan, and Medan, and Midian, and Ishbak, and Shuah. (KJV) I Chronicles 1:32  Now the sons of Keturah, Abraham's concubine: she bare Zimran, and Jokshan, and Medan, and Midian, and Ishbak, and Shuah. And the sons of Jokshan; Sheba, and Dedan. (KJV)

The word translated as 'wife' in the KJV is 'ishshah', which means 'woman'.  So Keturah was both a woman and a concubine.  Not a contradiction.