incessantness vs incessancy

incessantness and incessancy both are nouns.

Word	Noun	Adjective	Verb	Adverb
incessantness	Yes	No	No	No
incessancy	Yes	No	No	No

As nouns, incessantness and incessancy are synonyms defined as:

incessantness and incessancy: the quality of something that continues without end or interruption

Other synonyms of incessantness include ceaselessness, continuousness.

incessantness (noun)	incessancy (noun)
the quality of something that continues without end or interruption	the quality of something that continues without end or interruption