definition of
flatness

[1] #1 flatness n. [two-dimensionality, planeness] the property of having two dimensions. wn

[2] #2 flatness n. a want of animation or brilliance; "the almost self-conscious flatness of Hemingway's style". wn

[3] #3 flatness n. a deficiency in flavor; "it needed lemon juice to sharpen the flatness of the dried lentils". wn

[4] #4 flatness n. [lusterlessness, lustrelessness, mat, matt, matte] the property of having little or no contrast; lacking highlights or gloss. wn

[5] #5 flatness n. [languor, lethargy, sluggishness, phlegm] inactivity; showing an unusual lack of energy; "the general appearance of sluggishness alarmed his friends". wn