This famous Gaelic surname recorded in the spellings of MacLaughlin, MacLoughlin, MacClaughlin, MacLaughlin, MacGuaghlin, MacLoughen, MacLoglen, MacGlacken and many others, and also in the popular short forms using "Mc", such as McLoughlin, McCloughen, and McGauglin, is an the anglicization of a pre 10th century first name and borne by two entirely distinct clans or septs. The first sept was originally called O' Maoilsheachlann, and then was recorded as O'Melaghlin up to the end of the 17th Century. From 1691 and after the battle of the Biyne it became known as MacLoughun, although even this spelling is now largely extinct. The territory of this sept lay in the central plains of Ireland, especially in County Meath. The Gaelic prefix "O" indicates male descendant of, and "maol", the tonsured one, and refers to a follower of Saint Seachlann, although the clan claims descent from Malachy 11nd, High King of Ireland from 980 - 1002. The second sept belonged to the town of Innishowen, in County Donegal, and has a Viking ancestry. Here the name translates as "the son of Lochlann", a compound of the Norse elements "loch", meaning a lake or fjord, plus "lann" land. The great leading men of this sept are frequently referred to in "The Annals of the Four Masters", an early history of Ireland. The first recorded spelling of the family name is shown to be that of MacLochlann of Ulster, which was dated circa 1200, in the Annals of Medieval History for the counties of Donegal and Derry, during the reign of King Cathal Craobhdhearg, known as "The Red Hand", and High King of Ireland, 1198 - 1220. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.1224.