Aidan is the Anglicized form of the Irish Aodhan, a diminutive of Aodh, the old Celtic word for "fire", so it means "little fire" or "fiery one". Saint Aidan of Lindisfarne spread Christianity in northern England in the 7th century. In the United States Aidan peaked at number 39 in 2003 and has fallen as the spelling Aiden took over; it ranked 185th in 2015 and stands at 326 among boys' names in 2025.