Gordon
Gordon—This name has been assumed by an Irish sept called M'Gournaghan (Mac Guarnacháin) in Co. Mayo, and McGournosan in the districts surrounding Downpatrick, Co. Down, written also in Gaelic as above.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees