cool it vs simmer down

cool it and simmer down both are verbs.

Word	Noun	Adjective	Verb	Adverb
cool it	No	No	Yes	No
simmer down	No	No	Yes	No

As verbs, cool it and simmer down are synonyms defined as:

cool it and simmer down: become quiet or calm, especially after a state of agitation

Other synonyms of cool it include calm, calm down, chill out, cool off, settle down.

cool it (verb)	simmer down (verb)
become quiet or calm, especially after a state of agitation	become quiet or calm, especially after a state of agitation