rattle down vs rattle

rattle down is not a noun while rattle is a noun.

Word	Noun	Adjective	Verb	Adverb
rattle down	No	No	Yes	No
rattle	Yes	No	Yes	No

rattle down (noun)	rattle (noun)
	loosely connected horny sections at the end of a rattlesnake's tail
	a baby's toy that makes percussive noises when shaken
	a rapid series of short loud sounds (as might be heard with a stethoscope in some types of respiratory disorders)

rattle down (verb)	rattle (verb)
recite volubly or extravagantly	shake and cause to make a rattling noise
	make short successive sounds