Gilbeart
GILBEART—VIII—Gilbert; 'son of Gilbert,' a Norman personal name of Teutonic origin. It appears in Domesday Book in the Latin form of ' Gislebertus.' The diminutive Gibbon, in Irish Giobún, was the usual form of the name among the Anglo-Normans in Ireland, where, as a surname, Gilbert is not very old.
Alphabetical Index to Irish Surnames