late 15c. as a nickname for Alexander; it is a diminutive or familiar variant of the nickname Saunder, which is preserved in surnames, as in Clerk Saunders of the old Border ballad. As the typical name for a Scotsman (especially a Lowlander) from 1785; in that use also punning on the hair-color sense of sandy (adj.). Also Sawney.
updated on December 10, 2021