Ó Duinn
Ó DUINN—I—O Dunne, O Doyne, Dunne, Dunn, Dun, Doyne, Dyne, &c.; 'descendant of Donn' (brown). There are two distinct families of this name: (1) Ó Duinn of Ui Riagain, a branch of the Ui Failghe, and one of the chief families of Leinster. The head of this family was lord of Ui Riagain, now anglicised Iregan, which was co-extensive with the present barony of Tinnahinch, in Leix. (2) Ó Duinn of Tara. This family was dispossessed soon after the Anglo-Norman invasion. The name is now very common in Leinster and Munster.
Alphabetical Index to Irish Surnames