Longman Dictionary of Contemporary English
Wiktionary
n. A fat or oil, from either animal or vegetable sources, containing a high proportion of saturated fatty acids; will typically be solid at room temperature; a diet high in saturated rather than unsaturated fats is thought to contribute to higher levels of cholesterol in the blood.
Wikipedia
A saturated fat is a fat in which the fatty acids all have single bonds.
A fat is made of two kinds of smaller molecules: monoglyceride and fatty acids. Fats are made of long chains of carbon (C) atoms. Some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). Double bonds can react with hydrogen to form single bonds. They are called saturated, because the second bond is broken up and each half of the bond is attached to (saturated with) a hydrogen atom. Most animal fats are saturated. The fats of plants and fish are generally unsaturated. Saturated fats tend to have higher melting points than their corresponding unsaturated fats, leading to the popular understanding that saturated fats tend to be solids at body temperatures, while unsaturated fats tend to be liquid oils.
Various fats contain different proportions of saturated and unsaturated fat. Examples of foods containing a high proportion of saturated fat include animal fat products such as cream, cheese, butter, other whole milk dairy products and fatty meats which also contain dietary cholesterol. Certain vegetable products have high saturated fat content, such as coconut oil and palm kernel oil. Many prepared foods are high in saturated fat content, such as pizza, dairy desserts, and sausage.
The effect of saturated fat on risk of disease is controversial. Many reviews recommend a diet low in saturated fat and argue it will lower risks of cardiovascular diseases, diabetes, or death. However, other reviews have rejected those arguments or advocated for examining the proportion of saturated to unsaturated fat in the diet.