The basic conceptual building unit of a polymer; a molecule of low molecular weight which may combine with other molecules to form a molecule in a chain or branched form having high molecular weight; as, amino acids are the monomer units which are combined to form proteins; vinylic plastics are formed from monomers having a vinyl group.

A small molecule that is linked with large numbers of other small molecules to form a chain or a network (polymer).

An organic chemical unit linked to other units (usually by a covalent bond formed by the removal of water) to produce a larger molecule (macromolecule) known as a polymer.

A compound consisting of molecules each of which can provide one or more constitutional units.