This name is of Scottish locational origin from a place thus called in the parish of Westerkirk, Dumfriesshire. The name derives from the Welsh "glyn" meaning "valley", "dun", a fort, plus "gwyn" white or fair, hence, "the valley of the white fort". The surname from this source is first recorded in the latter half of the 13th Century (see below). In the "Miscellany of the Scottish Historical Society" one, William de Glendonwyn is recorded as "procurator of the Scottish Nation in the University of Orleans (1408)". In the "Criminal Trials of Scotland" from A.D. 1487 to 1624 reference is made to the stealing of goods from a Bartholomew Glendunwyne (1504) and in the reign of Charles 1 (1625 - 1649) a John Glendinning had his lands forfeited when Montrose, the Kings's lieutenant, whom he supported was defeated. The first recorded spelling of the family name is shown to be that of Adam de (of) Glendonwyn which was dated C.1386, in the "Records of the Baronies of Clifton and Merbrtel". during the reign of King Edward 1, known as "The Hammer of the Scots", 1272 - 1307. 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.