The name Keturah in the Bible
Keturah is the second wife of Abraham, whom he took after the death of his first wife Sarah (Genesis 25:1). We know surprisingly little about Keturah. We don't know from what nation she came, who her parents were or whether she outlived Abraham or not. Some Jewish sages have proposed that Keturah and Hagar, the mother of Ishmael, are the same person, but there's no evidence in the text to support this, and this proposition is ultimately fantastic. What we do know is that Keturah became to mother of six Abrahamic sons, one of whom, Midian, became a nation that rivaled Israel.
It's rarely noticed that Abraham complained that he was too old to have Isaac (Genesis 17:17), but when Isaac was 36 years old (compare 17:17 to 23:1) Sarah died, and some undisclosed time after, Abraham married Keturah and sired another six sons.
Etymology of the name Keturah
The name Keturah comes from the verb קטר (qatar) meaning to produce pleasant smoke:
NOBSE Study Bible Name List and Jones' Dictionary of Old Testament Proper Names agree: the name Keturah means Incense.