The chemical initiator of a polymerization process.
The basic molecular subunit from which, by repetition of a single reaction, polymers are made. For example, amino acids (monomers) link together via condensation reactions to yield polypeptides or proteins (polymers). A monomer is analogous to a link (monomer) in a metal chain (polymer).
A simple molecule of a compound of relatively low molecular weight.
Any molecule that can be bound to similar molecules to form a polymer.