quality of solvent

in polymer chemistry
A qualitative characterization of the polymer–solvent interaction. A solution of a polymer in a 'better' solvent is characterized by a higher value of the second virial coefficient than a solution of the same polymer in a 'poorer' solvent.
Purple Book, 1st ed., p. 57 (http://old.iupac.org/publications/books/author/metanomski.html)