stillness vs fixedness

stillness and fixedness both are nouns.

Word	Noun	Adjective	Verb	Adverb
stillness	Yes	No	No	No
fixedness	Yes	No	No	No

As nouns, fixedness is a hyponym of stillness; that is, fixedness is a word with a more specific, narrower meaning than stillness:

Other hyponyms of stillness include immobility, stationariness.

stillness (noun)	fixedness (noun)
(poetic) tranquil silence	the quality of being fixed in place as by some firm attachment
calmness without winds	the quality of being fixed and unchangeable
a state of no motion or movement	remaining in place