flatness

noun

1. the property of having two dimensions

   noun.attribute

   Synonyms planeness two-dimensionality

   Source: WordNet 3.0

2. a want of animation or brilliance

   noun.communication

   Examples

   The almost self-conscious flatness of Hemingway's style.

   Source: WordNet 3.0

3. a deficiency in flavor

   noun.cognition

   Examples

   It needed lemon juice to sharpen the flatness of the dried lentils.

   Source: WordNet 3.0

4. the property of having little or no contrast; lacking highlights or gloss

   noun.attribute

   Synonyms lusterlessness lustrelessness mat matt matte

   Source: WordNet 3.0

5. inactivity; showing an unusual lack of energy

   noun.attribute

   Synonyms languor lethargy phlegm sluggishness

   Source: WordNet 3.0

6. The quality or state of being flat.

   noun

   Source: webster1913