The Irish and Scottish surname MacDaid is of patronymic origin being an anglicized form of the Gaelic surname Mac Daibheid, meaning “son of David.” The MacDaid’s are said to have descended from David O'Doherty, a chief of Cinel Conaill, who was killed in 1208, and grew to be numerous in Inishowen. The name is found throughout Ireland with high numbers in counties Derry, Down and Donegal.