incessancy vs incessantness

incessancy and incessantness both are nouns.

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

As nouns, incessancy and incessantness are synonyms defined as:

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

Other synonyms of incessancy include ceaselessness, continuousness.

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