redundancy vs redundant

redundancy is a noun but redundant is not a noun.

Word	Noun	Adjective	Verb	Adverb
redundancy	Yes	No	No	No
redundant	No	Yes	No	No

redundancy (noun)	redundant (noun)
repetition of an act needlessly
the attribute of being superfluous and unneeded
(electronics) a system design that duplicates components to provide alternatives in case one component fails
repetition of messages to reduce the probability of errors in transmission

redundancy (adjective)	redundant (adjective)
	more than is needed, desired, or required
	repetition of same and identical sense with different and non-identical words