elephant yam vs aroid

elephant yam and aroid both are nouns.

Word	Noun	Adjective	Verb	Adverb
elephant yam	Yes	No	No	No
aroid	Yes	Yes	No	No

As nouns, aroid is a hypernym of elephant yam; that is, aroid is a word with a broader meaning than elephant yam:

elephant yam: putrid-smelling aroid of southeastern Asia (especially the Philippines) grown for its edible tuber
aroid: any plant of the family Araceae; have small flowers massed on a spadix surrounded by a large spathe

Other hypernyms of elephant yam include arum.

elephant yam (noun)	aroid (noun)
putrid-smelling aroid of southeastern Asia (especially the Philippines) grown for its edible tuber	any plant of the family Araceae; have small flowers massed on a spadix surrounded by a large spathe

elephant yam (adjective)	aroid (adjective)
	relating to a plant of the family Araceae