As Liam mc Devitt (and possibly others) correctly pointed out, the meaning of Mc Devitt, Mac Daibheid gaelic version, is "Son of David". The "David in question was David O Doherty, one of the chiefs of the clan Doherty of Inisowen, a peninsula in north Donegal situated between Lough Swilly and Lough Foyle. The Mc Devitt clan were "fostered" i.e. in the protection of the O Doherty clan and were considered "kinsmen" to the O Donnells who were the ruling chiefs of Donegal for many years, up to the "Flight of the Earls" c.1607. The O Doherty clan ruled the Inishowen peninsula and were equal to the O Donnells up to the time of the battle of Kilmacrennan c.1606 when Séan Óg(young) O Doherty was killed in battle. The O Doherty and the McDevitt clans lost their lands at that point and were forced to move towards the practically uninhabited wastelands of west Donegal.During the last decade of the seventeenth century there were 4 McDevitt brothers among the prominent allies of Séan Óg O Doherty during negotiations with the British commanders of the time. Their names were Aodh Buidhe Mc Devitt(golden haired Hugh, Séan Crón(sandy haired John),Eamonn Gruama(Dour Edward)and Feidhleimí Riabhach(tawny haired or tawny skinned Phelim I am directly descended from one of those brothers; there are conflicting reports as to which, but my own opinion is that I am descended from Aodh Buidhe, who married a spanish lady while living in Spain, having escaped there after the above mentioned battle, and brought the Christian name "Feardorcha" or Ferdinand into the family.I am one of the tenth generation directly descended from that man.