simmer down vs cool it

simmer down and cool it both are verbs.

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

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

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

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

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