The name Weir is of Scottish origin, derived from the Old English word 'were', which means 'ware' or 'aware'. It was originally a occupational surname given to a maker or repairer of wicker baskets and cages. The clan Weir are believed to have originated in Galloway, Scotland, and they were prominent landowners in that region during medieval times. Today, Weir is still predominantly found in Scotland, but it has also spread to other parts of the world through migration.
The name Weir experienced fluctuations in popularity between 1913 and 1929, with peaks in the mid-1910s and late 1920s. Notably, there was a significant increase from 5 births in 1922 to 10 births in 1923.