1) Glyceryl ester 1) Tributyrin 
Butyrin, also known as tributyrin, is a triglyceride naturally present in butter. It is an ester composed of butyric acid and glycerol. Among other things, it is used as an ingredient in making margarine. It is present in butter and can be described as a liquid fat with an acrid taste. Tributyrin is also used in microbiological laboratories to ide...
• (n.) A butyrate of glycerin; a fat contained in small quantity in milk, which helps to give to butter its peculiar flavor.
Bu'ty·rin noun (Physiol. Chem.) A butyrate of glycerin; a fat contained in small quantity in milk, which helps to give to butter its peculiar flavor. 
[n] - any of three glycerides of butyric acid
butyrin 1. A colorless liquid or oil found in butter and formed from butanoic acid and glycerol. 2. Butter fat contributing to the characteristic flavor of butter.
noun any of three glycerides of butyric acid
a colorless, liquid ester present in butter, formed from glycerin and butyric acid.