quieten vs calm

quieten is not a noun while calm is a noun.

Word	Noun	Adjective	Verb	Adverb
quieten	No	No	Yes	No
calm	Yes	Yes	Yes	No

As verbs, quieten and calm are synonyms defined as:

Other synonyms of quieten include calm down, lull, quiet, still, tranquilize, tranquillise, tranquillize.

quieten (noun)	calm (noun)
	steadiness of mind under stress
	wind moving at less than 1 knot; 0 on the Beaufort scale

quieten (adjective)	calm (adjective)
	(of weather) free from storm or wind
	not agitated; without losing self-possession

quieten (verb)	calm (verb)
cause to be quiet or not talk	cause to be calm or quiet as by administering a sedative to
make calm or still	make steady
become quiet or quieter	make calm or still
	become quiet or calm, especially after a state of agitation