Unsaturated Definition in Chemistry

In chemistry, the term unsaturated usually refers to one of two things: When referring to chemical  solutions, an unsaturated solution is able to dissolve more solute. In other words, the solution is not saturated. An unsaturated solution is more dilute than a saturated solution. When referring to organic compounds, unsaturated means a molecule contains double or triple carbon-carbon bonds. Examples of unsaturated organic molecules include HCCH and H2CO. In this context, being saturated can be thought of as being saturated with hydrogen atoms. Saturation can also refer to the percentage of protein binding sites that are filled or the lack of susceptibility of an organometallic compound to oxidative addition. Whenever the term saturation is used in chemistry, it refers to whether a phenomenon is close to maximum capacity. Source Badertscher, M.; Bischofberger, K.; Munk, M.E.; Pretsch, E. (2001). A Novel Formalism To Characterize the Degree of Unsaturation of Organic Molecules. Journal of Chemical Information and Modeling. 41 (4): 889. doi: 10.1021/ci000135o