Triglyceride. Chemically, an ester (q.v.) that combines one molecule of glycerol (q.v.) with three molecules of fatty acids (q.v.). It is representative of a category of fats (q.v.) and oils (q.v.), also referred to as lipids (q.v.), that constitutes one of nature's three major classes of organic compounds, the other two being the carbohydrates (q.v.) and the proteins (q.v.). When the three fatty acids in a triglyceride are the same, the result is a simple triglyceride, whereas when they differ, the result is the more prevalent mixed triglyceride. Triglycerides that are solid or have a plastic consistency at room temperature are referred to as fats (q.v.), whereas those that are liquid at this temperature are called oils (q.v.).