calm vs quieten

calm is a noun but quieten is not a noun.

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

As verbs, calm and quieten are synonyms defined as:

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

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

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

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