Source : Webster's Revised Unabridged Dictionary (1913)

Polyvalent \Po*lyv"a*lent\, a. [Poly- + L. valens, p. pr. See
   {Valent}.] (Chem.)
   Multivalent.

Source : WordNet®

polyvalent
     adj 1: containing several antibodies each capable of counteracting
            a specific antigen; "a polyvalent vaccine" [ant: {monovalent}]
     2: having more than one valence, or having a valence of 3 or
        higher [syn: {multivalent}] [ant: {monovalent}]