Ó Bríosáin
Ó BRÍOSÁIN—I—O Brisan, Briceson, Bryson; a corruption, in Co. Donegal, of Ó Muirgheasáin, which see. It is by no means a late corruption; Ó Brisan appears as the anglicised form in the Patent Rolls of James I.
Alphabetical Index to Irish Surnames