pen·ta·va·lent 
(pĕn′tə-vālənt)
(pĕn′tə-vālənt)adj.
1. Chemistry Having valence 5.
2. Immunology
a. Having five sites of attachment. Used of an antibody or antigen.
b. Containing antigens from five strains of a microorganism or virus. Used of a vaccine or serum.