Kennedy, with variant forms O'Kennedy and Kennedie, is a surname of Irish origin that has also been used as a given name.
Both of these personal names are derived from Gaelic words meaning "helmet-headed".
[1] Ceanéidigh could be related to the old Gaelic name Cennétig, which is known from Cennétig mac Lorcáin, the father of the Irish high king Brian mac Cennétig, who was also known as Brian Bóruma or Brian Boru.
Ceannéidigh is a given name derived from the Gaelic words ceann, meaning "head", and éidigh, meaning "ugly" or "fierce".
[2] Some etymologies also suggest that the element ceann could mean "chief" or "leader".