Morrissey, ó Muirgheasa
A Gaelic surname meaning descendant of Muirgheas (sea strength). A sept of the Uí Fiachrach who were formerly chiefs of a district on the southern shore of Sligo Bay, in the barony of Tireragh. In 1890 Morrissey was numerous in Waterford, it was also to be found in Limerick and Cork. The estimated number of bearers was 4,032 (including variants). In the United States Morrissey is the 2,524th most numerous surname with an estimated 13,750 bearers.