During which type of reaction do two molecules combine to form one and release water?

The process in which two molecules combine to form one larger molecule while releasing water is known as condensation. This reaction typically involves the joining of two smaller molecules, such as amino acids or sugars, through the formation of covalent bonds. The removal of a water molecule occurs during this process, which is essential for many biochemical pathways such as the formation of peptide bonds in proteins or glycosidic bonds in carbohydrates.

In the context of condensation reactions, they are often specifically termed "dehydration synthesis" because the synthesis involves the loss of water. While both condensation and dehydration synthesis refer to similar processes, the term "dehydration synthesis" is more specific to the loss of water during the formation of the new bond. Thus, your choice of condensation is correct as it captures the essence of the reaction taking place.