butterfat

the word is a modern english compound, transparently combining two ancient roots. "butter" traces back to greek boutyron, literally meaning "cow cheese," which passed through latin into old english. "fat" originates from the old english adjective fǣtt, describing an animal or substance rich in oily material. the compound "butterfat" logically emerged in the 19th century within dairy science to specify the particular fatty portion separated from milk, distinct from other components like water or protein. it directly names the substance that is the fat of or in butter and milk.

Structure: butter + fat butter: from old english butere, from latin butyrum, from greek boutyron (cow cheese). denotes a solid dairy product. fat: from old english fǣtt (fatted, plump), from proto-germanic faitidaz. denotes an oily or greasy substance.