fluidness vs thinness

fluidness and thinness both are nouns.

Word	Noun	Adjective	Verb	Adverb
fluidness	Yes	No	No	No
thinness	Yes	No	No	No

As nouns, thinness is a hypernym of fluidness; that is, thinness is a word with a broader meaning than fluidness:

fluidness (noun)	thinness (noun)
the property of flowing easily	the property of having little body fat
a changeable quality	relatively small dimension through an object as opposed to its length or width
	a consistency of low viscosity
	the property of being very narrow or thin
	the property of being scanty or scattered; lacking denseness
	The property of lacking substance or strength.