quieten vs quiet

quieten is not a noun while quiet is a noun.

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

As verbs, quieten and quiet are synonyms defined as:

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

As verbs, quieten and quiet are synonyms defined as:

Other synonyms of quieten include hush, pipe down, quiesce, quiet down.

quieten (noun)	quiet (noun)
	a disposition free from stress or emotion
	the absence of sound
	a period of calm weather
	an untroubled state; free from disturbances

quieten (adjective)	quiet (adjective)
	free of noise or uproar; or making little if any sound
	characterized by an absence or near absence of agitation or activity
	(of the sun) characterized by a low level of surface phenomena, such as sunspots
	(of a body of water) free from disturbance by heavy waves
	in a softened tone
	not showy or obtrusive

quieten (adverb)	quiet (adverb)
	with little or no activity or no agitation (`quiet' is a nonstandard variant for `quietly')