rattle vs rattle down

rattle is a noun but rattle down is not a noun.

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

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