A type of small polymer, a high-molecular-weight compound formed by the reacting and uniting—or polymerization—of a small number of monomers. An oligomer with only two monomers is called a dimer, one with three monomers is a trimer, etc. The polymerization of monomers and oligomers into much longer chain polymers is a means of drying and solidifying some printed inks, as well as producing many different synthetic resins used in the manufacture of printing ink.