cool down vs chill

cool down is not a noun while chill is a noun.

Word	Noun	Adjective	Verb	Adverb
cool down	No	No	Yes	No
chill	Yes	No	Yes	No

As verbs, cool down and chill are synonyms defined as:

Other synonyms of cool down include cool.

As verbs, cool down and chill are synonyms defined as:

Other synonyms of cool down include cool.

cool down (noun)	chill (noun)
	coldness due to a cold environment
	a sudden numbing dread
	an almost pleasurable sensation of fright
	a sensation of cold that often marks the start of an infection and the development of a fever