MORRISSEY Family History
This interesting surname has two distinct possible sources. Firstly, the surname may be of Irish origin, and is an Anglicized form of the Gaelic "O'Muirgheasa", descendant of "Muirgheasa", a personal name apparently derived from the elements "muir", sea, and "geas", action, and are a branch of the "Ui Fiachra", having their territory at the southern side of Sligo Bay. These are of MacDermot stock, being descended from Muiris, the grandson of a famous MacDermot. However, there is no Gaelic sept of Morrissey associated with Munster or Leinster.