flatness vs lusterlessness

flatness and lusterlessness both are nouns.

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

As nouns, flatness and lusterlessness are synonyms defined as:

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

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

flatness (noun)	lusterlessness (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