butterfat
natural fatty constituent of cows' milk and the chief component of butter. Clear butterfat rises to the top of melted butter and may be poured off, leaving the albuminous curd and water that favour the growth of organisms promoting rancidity; thus, anhydrous butterfat does not become rancid as readily as butter and can be stored unrefrigerated for several months. Butterfat is used in cooking and as a component in special dishes
Learn more about butterfat with a free trial on Britannica.com.