1. (chemistry) having more than one valence, or having a valence of 3 or higher
   "Iron is a polyvalent element, commonly existing in +2 and +3 oxidation states";
   - multivalent
    
2. (immunology) containing several antibodies each capable of counteracting a specific antigen
   "a polyvalent vaccine"

See also: valence, valency

Antonym: monovalent

Encyclopedia: Polyvalent