1. The property of having two dimensions
   "The flatness of a flat map can sometimes distort geographic relationships";
   - two-dimensionality, planeness
    
2. The property of having little or no contrast; lacking highlights or gloss
   "The flatness of the old painting made it difficult to appreciate its details";
   - lusterlessness [N. Amer], lustrelessness [Brit, Cdn], mat, matt, matte
    
3. A deficiency in flavour
   "it needed lemon juice to sharpen the flatness of the dried lentils"
    
4. Inactivity; showing an unusual lack of energy
   "the general appearance of flatness alarmed his friends";
   - languor, lethargy, sluggishness, phlegm
    
5. A want of animation or brilliance
   "the almost self-conscious flatness of Hemingway's style"
    
6. (music) the property of having a pitch lower than the proper tone
   "The singer's flatness ruined the performance"

Type of: dimensionality, dullness, expressive style, gustatory perception, gustatory sensation, inactiveness, inactivity, inertia, style, taste, taste perception, taste sensation

Encyclopedia: Flatness