oligomer \o*lig"o*mer\, n. (Chem.) A molecule composed of a small number of linked monomer units; a short polymer; -- compounds called oligomers have less than one hundred monomer units and usually less than thirty. Oligomers of increasing length are called {dimer}, {trimer}, {tetramer}, {pentamer}, {hexamer}, {heptamer}, {octamer}, {nonamer}, {decamer}, etc. In colloquial laboratory jargon, they may also be referred to as {nine-mer}, {ten-mer}, {eleven-mer}, {twelve-mer}, etc., especially for oligomers of greater than eight units. [PJC]