reversionary vs reversion

reversionary is not a noun while reversion is a noun.

Word	Noun	Adjective	Verb	Adverb
reversionary	No	Yes	No	No
reversion	Yes	No	No	No

reversionary (noun)	reversion (noun)
	a failure to maintain a higher state
	turning in the opposite direction
	returning to a former state
	(genetics) a return to a normal phenotype (usually resulting from a second mutation)
	a reappearance of an earlier characteristic
	(law) an interest in an estate that reverts to the grantor (or his heirs) at the end of some period (e.g., the death of the grantee)

reversionary (adjective)	reversion (adjective)
of or relating to or involving a reversion (especially a legal reversion)