The surname Sweeny is an Anglicized form of the Gaelic ‘Mac Suibhne’, and has its origins in Scotland. Meaning ‘pleasant or well-disposed’ the Gaelic name was also used as equivalent to the unrelated Old Norse personal name ‘Sveinn’, meaning “boy”, “servant”. The original ‘Mac Suibhne’ was a Scottish chief based in Argyle around the year 1200. His people were of mixed Irish and Viking blood and were noted fighters, which meant their services were in great demand in Ireland at the time, as mercenaries.
The family first settled in Ireland in the Flanad district of the modern Co. Donegal in the 14th century, and split into several distinct groups. For the next 400 years they fought as mercenaries in Ulster, mainly on behalf of the O’Donnells. The first recorded spelling of the name is that of Murrough Mac Sweeny who was one of the famous “galloglasses”. Written in Gaelic as “galloglach”, the word literally means “foreign young warrior” and denotes a mercenary soldier.