elephant ear vs arum

elephant ear and arum both are nouns.

Word	Noun	Adjective	Verb	Adverb
elephant ear	Yes	No	No	No
arum	Yes	No	No	No

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

elephant ear: any plant of the genus Alocasia having large showy basal leaves and boat-shaped spathe and reddish berries
arum: any plant of the family Araceae; have small flowers massed on a spadix surrounded by a large spathe

Other hypernyms of elephant ear include aroid.

elephant ear (noun)	arum (noun)
any plant of the genus Alocasia having large showy basal leaves and boat-shaped spathe and reddish berries	any plant of the family Araceae; have small flowers massed on a spadix surrounded by a large spathe
	starch resembling sago that is obtained from cuckoopint root