The bond that joins together three fatty acids and a glycerol molecule to form a triglyceride is called an "ester bond" or "ester linkage."
Triglycerides are a type of lipid (fat) molecule commonly found in organisms and serve as a storage form for energy. They consist of a glycerol molecule and three fatty acid molecules linked together by ester bonds through a chemical reaction known as esterification.
This process involves the removal of water molecules to form the ester bonds between the glycerol and the fatty acids.