decennary vs decade

decennary and decade both are nouns.

Word	Noun	Adjective	Verb	Adverb
decennary	Yes	No	No	No
decade	Yes	No	No	No

As nouns, decennary and decade are synonyms defined as:

Other synonyms of decennary include decennium.

decennary (noun)	decade (noun)
a period of 10 years	the cardinal number that is the sum of nine and one; the base of the decimal system
	a period of 10 years