poikilotherm vs poikilothermous

poikilotherm is a noun but poikilothermous is not a noun.

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

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

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