rampant vs rearing

rampant is not a noun while rearing is a noun.

Word	Noun	Adjective	Verb	Adverb
rampant	No	Yes	No	No
rearing	Yes	Yes	No	No

As adjectives, rampant and rearing are synonyms defined as:

rampant and rearing: rearing on left hind leg with forelegs elevated and head usually in profile

rampant (noun)	rearing (noun)
	helping someone grow up to be an accepted member of the community
	the properties acquired as a consequence of the way you were treated as a child

rampant (adjective)	rearing (adjective)
(of a plant) having a lush and unchecked growth	rearing on left hind leg with forelegs elevated and head usually in profile
rearing on left hind leg with forelegs elevated and head usually in profile
unrestrained and violent