still vs quieten

still is a noun but quieten is not a noun.

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

As verbs, still and quieten are synonyms defined as:

Other synonyms of still include hush, hush up, shut up, silence.

As verbs, still and quieten are synonyms defined as:

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

still (noun)	quieten (noun)
an apparatus used for the distillation of liquids; consists of a vessel in which a substance is vaporized by heat and a condenser where the vapor is condensed
a static photograph (especially one taken from a movie and used for advertising purposes)
a plant and works where alcoholic drinks are made by distillation
(poetic) tranquil silence

still (adjective)	quieten (adjective)
not sparkling
used of pictures; of a single or static photograph not presented so as to create the illusion of motion; or representing objects not capable of motion
(of a body of water) free from disturbance by heavy waves
marked by absence of sound
not in physical motion
free from noticeable current

still (verb)	quieten (verb)
cause to be quiet or not talk	cause to be quiet or not talk
make motionless	make calm or still
make calm or still	become quiet or quieter
lessen the intensity of or calm

still (adverb)	quieten (adverb)
to a greater degree or extent; used with comparisons
with reference to action or condition; without change, interruption, or cessation
without moving or making a sound
despite anything to the contrary (usually preceding a concession)