waterfall vs cataract

waterfall and cataract both are nouns.

Word	Noun	Adjective	Verb	Adverb
waterfall	Yes	No	No	No
cataract	Yes	No	No	No

As nouns, cataract is a hyponym of waterfall; that is, cataract is a word with a more specific, narrower meaning than waterfall:

Other hyponyms of waterfall include cascade.

waterfall (noun)	cataract (noun)
a steep descent of the water of a river	a large waterfall; violent rush of water over a precipice
	an eye disease that involves the clouding or opacification of the natural lens of the eye