poikilothermous vs poikilotherm

poikilothermous is not a noun while poikilotherm is a noun.

Word	Noun	Adjective	Verb	Adverb
poikilothermous	No	Yes	No	No
poikilotherm	Yes	No	No	No

poikilothermous (noun)	poikilotherm (noun)
	an animal whose body temperature varies with the temperature of its surroundings; any animal except birds and mammals

poikilothermous (adjective)	poikilotherm (adjective)
of animals except birds and mammals; having body temperature that varies with the environment