fastness vs gradualness

fastness and gradualness both are nouns.

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

As nouns, gradualness is a hyponym of fastness; that is, gradualness is a word with a more specific, narrower meaning than fastness:

fastness: a rate (usually rapid) at which something happens
gradualness: the quality of being gradual or of coming about by gradual stages

Other hyponyms of fastness include haste, hastiness, hurriedness, hurry, precipitation, execution speed, graduality.

fastness (noun)	gradualness (noun)
a strongly fortified defensive structure	the quality of being gradual or of coming about by gradual stages
a rate (usually rapid) at which something happens	the property possessed by a slope that is very gradual
the quality of being fixed in place as by some firm attachment