WordWeb Online

1. Straighten up or out; make straight
   - straighten
    
2. Unfasten, as a sail, from a spar or a stay
    
3. Free from flexure
   "unbend a bow"
    
4. Make less taut
   - relax
    
5. Become less tense, rest, or take one's ease
   - relax, loosen up, unwind, decompress, slow down
    
6. Release from mental strain, tension, or formality
   "unbend the mind from absorbing too much information"

Derived forms: unbent, unbending, unbends

Type of: change posture, change state, loose, loosen, loosen up, make relaxed, relax, straighten, straighten out, turn, unfasten, unlax, unstrain, unwind

Antonym: bend