Abbot
As the name implies it may have derived from the title Abbot (of a monastery) or from people employed in an abbey. It was probably introduced into Ireland after the coming of Christianity when abbeys were first erected. The name may have declined in Ireland in the 15th century after the dissolution of the monasteries by the order of King Henry VIII. In the 1911 census there were only 31 people of that name living in Ireland.
Adair
This name was introduced into Ireland during the time of the Ulster Plantation. In the census of 1911 the vast majority of the 1320 Adairs living in Ireland were still living in the counties of Northern Ireland. According to some sources the name is the name of a Scottish sept and part of the Clan Maxwell.
Aherne
The name Aherne is derived from the Gaelic name O’Hagherin. This Gaelic sept was based in the Six Mile Bridge area of modern Co. Clare. They are said to be descended from Brian Boru the High King of all Ireland who was killed in the Battle of Clontarf in 1014. The most famous man of that name in modern times is Bertie Ahern who was Taoiseach of Ireland 1997-2008. Mr. Ahern was one of the principal architects of the Good Friday Agreement.