Multivalent \Mul*tiv"a*lent\, a. [Multi- + L. valens, p. pr. See
   {Valence}.]
   1. (Chem.)
      (a) Having a valence greater than one, as silicon.
      (b) Having more than one degree of valence, as sulphur.
          
[1913 Webster]


   2. (Immunology) Having multiple antigen-binding sites; -- of
      antibody molecules.
      [PJC]

   3. (Immunology) Containing several types of antibody, to
      protect against more than one disease; polyvalent; -- of
      vaccines.
      [PJC]