A mattress cover is an item of bedding that is placed over a mattress to protect it from dirt, dust, and other debris. The two crossword solutions for the term 'mattress cover' are 'SHEET' and 'TICK'. A SHEET is a large rectangular piece of fabric used as bedding, usually made of cotton or linen. A TICK is a type of fabric that is tightly woven and has a smooth surface, often used for upholstery and mattress covers.