flatness

noun6

1. •
   The state of being flat

   • The flatness of the landscape facilitates views right across the Firth of Forth to Fife, before the railway begins to pierce the Edinburgh suburbs. — 2022
2. •
   The state of being two-dimensional; planar : planarity
3. •
   The state of being bland : dullness
4. •
   Lack of bouquet and freshness of a wine, through too much aeration or infection with film yeasts
5. •
   Mattness, the quality of a painted surface which scatters or absorbs the light falling on it, so as to be substantially free from gloss or sheen
6. •
   slim-tailedness or platykurtosis.