1.A liquid oil made from animal fats (esp. beef fat) by separating the greater portion of the solid fat or stearin, by crystallization. It is mainly a mixture of olein and palmitin with some little stearin. (archaic)
2.An artificial butter made by emulsifying a fatty oil with more or less milk and water; it was formerly made predominantly from animal fats, but now is made predominantly or exclusively from vegetable oils, sometimes mixed with animal fats. Note: Oleomargarine was wrongly so named, as it contains no margarin proper, but olein, palmitin, and stearin, a mixture of palmitin and stearin having formerly been called margarin by mistake.