A duvet (/ˈdjuːveɪ/, /ˈduːveɪ/, or US /duːˈveɪ/; from the French duvet [dyvɛ] "down") is a type of bedding consisting of a soft flat bag filled with down, feathers, wool, silk or a synthetic alternative, and typically protected with a removable cover, analogous to a pillow and pillow case. Sleepers often use a duvet without a top bed sheet, as the duvet cover can readily be removed and laundered as often as the bottom sheet. In Australian English, it is also called a doona. In American English, it may be called a comforter; however, a comforter is usually a slightly different type of bedding that is not as thick, does not have a cover, and is often used over a top sheet.