Recorded in the spelling of Keilty, Kiltie, Kilty, and Quilty, this Irish surname is an anglicized form of the ancient Gaelic name O'Caoilte or sometimes MacCaoilte. The prefix "O" indicates "descendant of", which "Mac" is more direct and describes the "son of", plus in this case the personal name Caoilte, thought to be derived from the Gaelic element "coill" meaning a "wood" or more likely "caol" meaning "the slender one", and presumably a nickname for the first chief of the clan. The majority of Irish surnames derive from the nicknames of the chiefs, some being by modern standards rude or even lewd! The surname is mainly found in the province of Munster and then in counties Limerick, Waterford and Tipperary. In the 20th century "O" prefix has almost invariably been dropped, but the dialectal spelling of MacQuilty or McQuilty is occasionally to be found in the Ulster county of Antrim.The first recorded spelling of the family name is believed to be that of Teag O'Kilte, in the rolls and registers of the County Limerick Justiciary Rolls. This was during the reign of King Edward ll of England, 1307 - 1327. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.