WordNet (r) 3.0 (2006):

polyvalence
    n 1: (chemistry) the state of having a valence greater than two
         [syn: polyvalence, polyvalency, multivalence,
         multivalency]
    2: (toxicology) the state of being capable of counteracting more
       than one toxin or antigen or kind of microorganism [syn:
       polyvalence, polyvalency]