The Collaborative International Dictionary of English v.0.48:
Monovalent \Mo*nov"a*lent\, a. [Mono- + L. valens, p. pr. See Valence.] (Chem.) Having a valence of one; univalent. See Univalent. [1913 Webster]WordNet (r) 3.0 (2006):
monovalent adj 1: containing only one kind of antibody [ant: polyvalent] 2: having a valence of 1 [syn: monovalent, univalent] [ant: multivalent, polyvalent]