Main Entry: poly·va·lent Pronunciation: "päl-i-'vA-l&nt Function: adjective 1 a: having a chemical valence greater usuallythan two b: having variable valence 2: effective against, sensitive toward, or counteracting more than one exciting agent (as a toxin or antigen) polyvalent vaccine> —poly·va·lence/-l&n(t)s/noun