Ó Catháin
Ó CATHÁIN—I—O Caghane, O Cahaine, O Cahane, O Kahane, O Kaane, O'Cahan, O'Caughan, O'Kane, O'Keane, Cahane, Cahan, Cane, Cain, Kane, Keane, &c.; 'descendant of Cathán' (a 'pet' form of some name commencing with Cath-); the name (1) of a branch of the Cinel Eoghain, who were lords of Keenaght and possessed the greater part of the present Co. Derry until their estates were confiscated at the time of the plantation of Ulster; and (2) of a branch of the Ui Fiachrach in Co. Galway. A branch of the Derry family is said to have settled at an early period in Thomond. There are no doubt several distinct families of the name which is now a very common one all over Ireland.
Alphabetical Index to Irish Surnames