ataraxis vs quietness

ataraxis and quietness both are nouns.

Word	Noun	Adjective	Verb	Adverb
ataraxis	Yes	No	No	No
quietness	Yes	No	No	No

As nouns, quietness is a hypernym of ataraxis; that is, quietness is a word with a broader meaning than ataraxis:

Other hypernyms of ataraxis include quietude, tranquility, tranquillity.

ataraxis (noun)	quietness (noun)
the absence of mental stress or anxiety	the property of making no sound
	a state of peace and quiet