This is an anglicization of an Olde Scots Gaelic name MacSuibhne meaning 'son of Suibhne' - a compound of the Gaelic elements 'mac' meaning 'son' and the personal name Suibhne translating as 'pleasant' or 'well-going'. One Suibhne was Lord of Knapdale (Scotland at the beginning of the 13th century). His descendants came to Donegal as gollowglasses (hired soldiers) in the 14th century and formed three septs in Ireland. MacSweeny Fanad, MacSweeny Banagh and MacSweeny na dTuath. The latter meaning 'of the districts' (in Donegal). A branch of the former migrated to Munster c. 1500 and established themselves in counties Cork and Kerry. The name is also spelt MacSweeney or MacSwinney (often without the prefix 'mac'). The first recorded spelling of the family name is shown to be that of Murrough MacSweeny (MacSuibhne in Gaelic) which was dated post 1300 The Annals of the Four Masters during the reign of King Edward 1 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.