simmer down vs cool off

simmer down and cool off both are verbs.

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

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

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

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

simmer down (verb)	cool off (verb)
become quiet or calm, especially after a state of agitation	lose intensity
	become quiet or calm, especially after a state of agitation
	feel less enamoured of something or somebody