noun the quality or state of being flat.
2. flatness ·noun want of variety or flavor; dullness; insipidity.
3. flatness ·noun want of vivacity or spirit; prostration; dejection; depression.
4. flatness ·noun eveness of surface; want of relief or prominence; the state of being plane or level.
5. flatness ·noun depression of tone; the state of being below the true pitch;
opposed to sharpness or acuteness.