flatness

noun

1.
the property of having two dimensions
NL vla planeness two-dimensionality
Derived from:
flat
2.
a want of animation or brilliance
Derived from:
flat
3.
a deficiency in flavor
Derived from:
flat
4.
the property of having little or no contrast; lacking highlights or gloss
lusterlessness lustrelessness mat matt matte
Derived from:
flat
5.
inactivity; showing an unusual lack of energy
languor lethargy phlegm sluggishness