negativism vs negativeness

negativism and negativeness both are nouns.

Word	Noun	Adjective	Verb	Adverb
negativism	Yes	No	No	No
negativeness	Yes	No	No	No

As nouns, negativism and negativeness are synonyms defined as:

negativism and negativeness: characterized by habitual skepticism and a disagreeable tendency to deny or oppose or resist suggestions or commands

Other synonyms of negativism include negativity.

negativism (noun)	negativeness (noun)
characterized by habitual skepticism and a disagreeable tendency to deny or oppose or resist suggestions or commands	characterized by habitual skepticism and a disagreeable tendency to deny or oppose or resist suggestions or commands
	an amount less than zero
	the character of the negative electric pole