ultimateness vs ultimacy

ultimateness and ultimacy both are nouns.

Word	Noun	Adjective	Verb	Adverb
ultimateness	Yes	No	No	No
ultimacy	Yes	No	No	No

As nouns, ultimateness and ultimacy are synonyms defined as:

ultimateness and ultimacy: the state or degree of being ultimate; the final or most extreme in degree or size or time or distance

ultimateness (noun)	ultimacy (noun)
the state or degree of being ultimate; the final or most extreme in degree or size or time or distance	the state or degree of being ultimate; the final or most extreme in degree or size or time or distance