A relatively short (the prefix “oligo-” means few, slight) chain molecule (polymer) that is made up of repeating units (e.g., XAXAXAXA or XXAAXXAAXXAA, etc.). Short polymers consisting of only two repeating units are called dimers, those of three repeating units are called trimers. Longer units are called polymers (i.e., many units). As a rule of thumb, oligomers consisting of eleven or more repeating units are called polymers.
Short chain of monomer liquids that is often thick, sticky, and gel-like and that is not long enough to be considered a polymer.