u·ni·va·lent 
(y′nĭ-vālənt)
(y′nĭ-vālənt)adj.
1. Chemistry
a. Having valence 1, regardless of whether the valence is positive or negative.
b. Having only one valence.
2. Genetics Of or relating to a chromosome that is not paired or united with its homologous chromosome during synapsis.
3. Immunology Having only one site of attachment. Used of an antibody or antigen.
4. Immunology Containing antigens from a single strain of a microorganism or virus. Used of a vaccine or serum.
n.
Genetics
Genetics
A univalent chromosome.