unsaturated fat

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A fat derived from plant and some animal sources, especially fish, that is liquid at room temperature. Intake of foods containing more unsaturated fats than saturated fats may contribute to reduced blood cholesterol levels.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A fat or oil, from either animal or vegetable sources, containing a high proportion of unsaturated fatty acids; will typically be liquid at room temperature; a diet high in unsaturated rather than saturated fats is thought to contribute to lower levels of cholesterol in the blood.