Plaid is a fabric pattern consisting of criss-crossed horizontal and vertical bands in multiple colors. It is most commonly associated with traditional Scottish kilts, but it has also been used in a variety of other garments throughout history. The term 'PLAID' comes from the Scottish Gaelic word for blanket, which is 'plaide'. The answer to the crossword puzzle is 'GLEN', which is a Scottish term for a narrow valley or ravine.