waterway vs rapid

waterway and rapid both are nouns.

Word	Noun	Adjective	Verb	Adverb
waterway	Yes	No	No	No
rapid	Yes	Yes	No	No

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

Other hyponyms of waterway include ditch, mare clausum, mare liberum.

waterway (noun)	rapid (noun)
a conduit through which water flows	a part of a river where the current is very fast
a navigable body of water

waterway (adjective)	rapid (adjective)
	done or occurring in a brief period of time
	characterized by speed; moving with or capable of moving with high speed