reversion vs reversionary

reversion is a noun but reversionary is not a noun.

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

reversion (noun)	reversionary (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)

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