A fitted sheet is one of the essential bedding items that we use every day. It is a sheet that is designed to fit snugly around your mattress, with elasticated edges that keep it secure in place. Synonyms for fitted sheet include bottom sheet, bed sheet, mattress sheet, and fit sheet. The bottom sheet refers to the sheet that covers the mattress's bottom while bedsheet is a generic term that can encompass any type of sheet that you put on your bed. The term mattress sheet is used interchangeably with a fitted sheet, and a fit sheet is another commonly used term for fitted sheets. In short, all of these terms refer to the same thing, a sheet designed to fit tightly around the mattress.