WordWeb Online

1. Having been made flat or flatter
   - planate

1. Make flat or flatter
   "flatten your stomach with these exercises";
   - pancake
    
2. Become flat or flatter
   "The landscape flattened";
   - flatten out, pancake
    
3. (music) lower the pitch of (musical notes)
   - drop

See also: planar, two-dimensional

Type of: alter, change, change form, change shape, deform, form, modify, shape

Antonym: sharpen

Encyclopedia: Flatten