ataraxis vs tranquillity

ataraxis and tranquillity both are nouns.

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

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

Other hypernyms of ataraxis include quietness, quietude, tranquility.

ataraxis (noun)	tranquillity (noun)
the absence of mental stress or anxiety	a disposition free from stress or emotion
	a state of peace and quiet
	an untroubled state; free from disturbances