The origin of this Gaelic name appears to be a variation of Edzaer and the first of the name is generally held to have been a son of Duvenald, a leader at the Battle of the Standard in 1138 and grandson of Donegal of Morton Castle, a descendant of whose had a charter from Robert the Bruce of the lands of Kildonan. Sir Andrew Agnew states, in his work on the hereditary sheriffs of Galloway, that ‘in the Lochnaw charter chest various deeds prove the name Edzaer and Adair to have been interchangeable with the Galloway Adairs. In a charter dated 1625 the name is spelt in both forms on the same page’. Many of the Galloway Adairs went to Ulster during the time of the Elizabethan plantation and settled mainly in County Antrim. One Patrick Adair who settled in Antrim around 1641 became famous as the author of a major work on the rise of the Presbyterian Church in Ireland.
James Adair, who died around 1783, was an American pioneer and wrote one of the earliest histories of the American Indians. The principal families recorded in the registers at the Lyon Court are those of Kinhilt and Genoch. Sir Robert Shafto Adair descended from the house of Kinhilt was created a baronet on 2 August 1838 and his son was raised to the peerage as Baron Waveney of South Elmham, Suffolk. The peerage became extinct but the baronetcy devolved upon a younger brother, whose line continues to this day.