Libby is a diminutive of Isabel or Elizabeth. Elizabeth originates in Hebrew language and means "promise of God". Elizabeth has been one of the most popular feminine given names over centuries and in various languages and various spellings it has almost a hundred different forms. In the Bible, Elizabeth was the mother of John Baptist and the wife of Zacharias. It was also popularized by Elizabeth I, the Virgin Queen of England, and Elizabeth II, current Queen of the Commonwealth realms.