turn down vs bounce

turn down is not a noun while bounce is a noun.

Word	Noun	Adjective	Verb	Adverb
turn down	No	No	Yes	No
bounce	Yes	No	Yes	No

As verbs, bounce is a hyponym of turn down; that is, bounce is a word with a more specific, narrower meaning than turn down:

Other hyponyms of turn down include dishonor, dishonour.

turn down (noun)	bounce (noun)
	a light, self-propelled movement upwards or forwards
	the quality of a substance that is able to rebound
	rebounding from an impact (or series of impacts)

turn down (verb)	bounce (verb)
make lower or quieter	eject from the premises
take a downward direction	hit something so that it bounces
reject with contempt	spring back; spring away from an impact
not accept as true	leap suddenly
refuse entrance or membership	move up and down repeatedly
	come back after being refused
	refuse to accept and send back