Caomhánach
CAOMHÁNACH—X—Cavanagh, Kavanagh, etc.; Irish 'Caomhánach,' i.e., belonging to Caomhán. This family derives its name and descent from Domhnall Caomhanach, son of Diarmaid Mac Murchadha who was King of Leinster at the time of the Anglo-Norman invasion. He was so called from having been fostered by the comharb or successor of St. Caomhán at Kilcavan, near Gorey; and the agnomen, contrary to the usual Irish practice, has for many centuries been adopted as a surname by his descendants. Modern writers sometimes wrongly prefix an Ó to this surname, making it Ó Caomhánaigh. The patrimony of the family lay in the present counties of Carlow and Wexford, where the name is now very common.
Alphabetical Index to Irish Surnames