polyvalent vs polyvalency

polyvalent is not a noun while polyvalency is a noun.

Word	Noun	Adjective	Verb	Adverb
polyvalent	No	Yes	No	No
polyvalency	Yes	No	No	No

polyvalent (noun)	polyvalency (noun)
	(chemistry) the state of having a valence greater than two
	(toxicology) the state of being capable of counteracting more than one toxin or antigen or kind of microorganism

polyvalent (adjective)	polyvalency (adjective)
having more than one valence, or having a valence of 3 or higher
containing several antibodies each capable of counteracting a specific antigen