The name Adair has its origins in the Gaelic language, derived from the Old Irish word "athar," meaning "ford" or "shallow crossing." It is believed to have originated in the medieval period, when it was used as a topographic surname referring to someone who lived near a ford or a shallow river crossing.

The earliest recorded use of Adair as a first name dates back to the 12th century in Scotland, where it was primarily used as a surname by families living in the Scottish Lowlands. One of the earliest documented references to the name is in the Ragman Rolls of 1296, a record of homage sworn to King Edward I of England by Scottish nobles and landowners.

In the 16th century, the name gained prominence with the rise of the Adair family, a Scottish clan based in County Antrim, Ireland. The most notable member of this family was Sir Robert Adair (1763-1855), a British diplomat and politician who served as Ambassador to the Ottoman Empire and later as Governor of Bombay.

Another influential figure bearing the name Adair was John Adair (1757-1840), an American soldier and politician who fought in the American Revolutionary War and later served as Governor of Kentucky from 1820 to 1824.

In the realm of literature, Adair appears in the works of Scottish novelist and poet Sir Walter Scott (1771-1832), who featured characters with this name in his novels, such as "The Bride of Lammermoor" and "The Heart of Midlothian."

One of the most famous bearers of the name Adair in the 20th century was Adair Craigmill (1913-1989), an American journalist and author known for her work as a war correspondent during World War II and the Korean War.

Another notable figure was Adair Crawford (1748-1795), an American pioneer and Revolutionary War soldier who played a significant role in the settlement of Kentucky and Tennessee.

While the name Adair has its roots in Scotland and Ireland, it has also been adopted and used in other parts of the world, particularly in North America and Australia, where it has gained popularity as a given name for both males and females.