This is a type of chemical reaction that involves the loss of water from the reacting molecules. In biological systems, it usually refers to the production of larger, biomolecules or polymers from smaller monomers.

This type of reaction is called dehydration reaction or dehydration synthesis.

The example is the synthesis of disaccharides. When two monosaccharides, such as glucose and fructose, join together (to form sucrose) they form glycosidic linkage via dehydration reaction, the water is released.