Nairn (nârn) [key], town (1991 pop. 7,721), Highland, N Scotland, at the mouth of the Nairn River on Moray Firth. It is a tourist resort and fishing harbor. Other industries include dairy and crop farming and whiskey distilling. Granite is quarried. Cawdor Castle, the legendary scene of the murder of Duncan by Macbeth, is located nearby.