flatness vs matt

flatness and matt both are nouns.

Word	Noun	Adjective	Verb	Adverb
flatness	Yes	No	No	No
matt	Yes	Yes	No	No

As nouns, flatness and matt are synonyms defined as:

flatness and matt: the property of having little or no contrast; lacking highlights or gloss

Other synonyms of flatness include lusterlessness, lustrelessness, mat, matte.

flatness (noun)	matt (noun)
the property of having two dimensions	the property of having little or no contrast; lacking highlights or gloss
inactivity; showing an unusual lack of energy
the property of having little or no contrast; lacking highlights or gloss
a deficiency in flavor
a want of animation or brilliance

flatness (adjective)	matt (adjective)
	not reflecting light; not glossy