From Scottish Gaelic, possibly meaning 'oak tree ford,' or an Anglicization of the Gaelic name Edgar.
Adair is a name of Scottish and Irish origin that began as a surname before making its way into use as a given name. The most widely accepted etymology traces it to a Scottish Gaelic form of the Old English personal name 'Eadgar' — itself from 'ead' (wealth, fortune) and 'gar' (spear) — which, filtered through Gaelic phonology, produced 'Adair.' An alternative derivation connects it to the Scots-Gaelic 'ath dair,' meaning 'ford of the oak tree,' a topographic surname describing a specific landscape feature that would have identified a family's place of origin in the Scottish Lowlands or Ulster.
As a surname, Adair appears throughout Scottish and Scots-Irish history, most notably in the form of Robert Adair, the 18th-century British surgeon whose friendship with the statesman Charles James Fox was later celebrated in verse. The Adair family of Genoch in Ayrshire were prominent enough that their name passed into Irish planter families during the Ulster Plantation. In America, the Scots-Irish diaspora carried the name across Appalachia and into the frontier South, where it attached itself to counties, rivers, and towns — Adair County exists in Kentucky, Missouri, Oklahoma, and Iowa, testament to the migrating communities that bore it.
As a given name, Adair has attracted modern parents drawn to its Celtic crispness and its gender-fluid sound — it sits comfortably on children of any gender without forcing itself into a category. It has a clan-badge quality, evoking windswept moors and clan loyalty, without the more common Celtic names' overexposure. Literary and musical figures named Adair remain few, which leaves the name open and unhaunted, ready to be defined by whoever carries it next.