Word that literally means “many parts.” Any of numerous compounds having a high molecular weight, either from being composed of many smaller molecules or by condensing many small molecules into larger molecules that can take on new forms and perform different functions. Plastic is an example of polymer technology, as is nylon. Polymers do not have a defined formula because they consist of various chains of different lengths. Natural polymers exist, too; examples are polysaccharides, rubber, and cellulose. The human body contains many polymers in the form of various proteins, nucleic acids, and the energy source glycogen. Hundreds, if not thousands, of cosmetic ingredients with various functions have been created based on the evolving science of polymers.