gradualness vs gradient

gradualness and gradient both are nouns.

Word	Noun	Adjective	Verb	Adverb
gradualness	Yes	No	No	No
gradient	Yes	No	No	No

As nouns, gradient is a hypernym of gradualness; that is, gradient is a word with a broader meaning than gradualness:

gradualness: the property possessed by a slope that is very gradual
gradient: the property possessed by a line or surface that departs from the horizontal

Other hypernyms of gradualness include slope.

gradualness (noun)	gradient (noun)
the quality of being gradual or of coming about by gradual stages	the property possessed by a line or surface that departs from the horizontal
the property possessed by a slope that is very gradual	a graded change in the magnitude of some physical quantity or dimension