unceasing vs constant

unceasing is not a noun while constant is a noun.

Word	Noun	Adjective	Verb	Adverb
unceasing	No	Yes	No	No
constant	Yes	Yes	No	No

As adjectives, unceasing and constant are synonyms defined as:

unceasing and constant: uninterrupted in time and indefinitely long continuing

Other synonyms of unceasing include ceaseless, incessant, never-ending, perpetual, unremitting.

unceasing (noun)	constant (noun)
	a quantity that does not vary
	a number representing a quantity assumed to have a fixed value in a specified mathematical context

unceasing (adjective)	constant (adjective)
uninterrupted in time and indefinitely long continuing	steadfast in purpose or devotion or affection
continuing forever or indefinitely	uninterrupted in time and indefinitely long continuing
	unvarying in nature