The Collaborative International Dictionary of English v.0.48:

Polymer \Pol"y*mer\, n. [See Polymeric.] (Chem.)
   Any one of two or more substances related to each other by
   polymerism; specifically, a substance produced from another
   substance by chemical polymerization. [Formerly also written
   polymere.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

polymer
    n 1: a naturally occurring or synthetic compound consisting of
         large molecules made up of a linked series of repeated
         simple monomers

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "polymer":
   acid, acidity, adhesive, agent, alkali, alkalinity, alloisomer,
   anion, antacid, atom, base, biochemical, cast plastic, cation,
   cellulose plastic, chemical, chemical element, chromoisomer,
   compound, copolymer, dimer, element, extruded plastic,
   heavy chemicals, high polymer, homopolymer, hydracid,
   inorganic chemical, ion, isomer, laminate, macromolecule, metamer,
   molded plastic, molding compounds, molecule, monomer, neutralizer,
   nonacid, organic chemical, oxyacid, plastic, protein plastic,
   pseudoisomer, radical, reagent, resin plastic, sulfacid, synthetic,
   synthetic fabric, synthetic rubber, thermoplastic,
   thermosetting plastic, trimer