fat

fat 1 Along with proteins and carbohydrates, one of the three nutrients used as energy sources by the body. The energy produced by fats is 9 calories per gram. Proteins and carbohydrates each provide 4 calories per gram. 2 Total fat; the sum of saturated, monounsaturated, and polyunsaturated fats. 3 A slang term for obese or adipose. 4 In chemistry, a compound formed from chemicals called fatty acids. These fats are greasy, solid materials found in animal tissues and in some plants. 5 A kind of body tissue that contains fats stored as energy that also insulates and cushions internal organs, also known as adipose tissue.