In biology, synthesis refers to the process of combining two or more components to produce an entity. In biochemistry, synthesis specifically refers to the production of an organic compound in a living thing, especially as aided by enzymes. There are several syntheses occurring in the cell or organism, and the creation of an organic compound in a living organism is referred to as biosynthesis. One example of synthesis in biology is photosynthesis, which is the synthesis of complex organic material using carbon dioxide, water, inorganic salts, and light energy captured by light-absorbing pigments such as chlorophyll and other accessory pigments. In other relevant fields, such as chemistry, synthesis refers to the act or process of forming a complex substance by combining or integrating two or more chemical entities, especially through a chemical reaction.

Therefore, in biology, synthesis refers to the production of an organic compound in a living thing, especially as aided by enzymes.