1. Settle or make right
   "we need to straighten out our disagreements";
   - iron out, put right
    
2. Change one's behaviour or beliefs for the better
   "The lazy student promised to straighten out";
   - reform, see the light
    
3. Make clear or more understandable; remove confusion or ambiguity
   "Can you straighten out this mess of regulations";
   - clear, clear up, shed light on, crystallize, crystallise [Brit], crystalize [US, rare], sort out, enlighten, illuminate, elucidate
    
4. Make straight
   "She straightened out the bent wire";
   - straighten
    
5. Extricate from entanglement
   "Can you straighten out the cord?";
   - disentangle, unsnarl
    
6. Put (things or places) in order
   "We need to straighten out the garage";
   - tidy, tidy up, clean up, neaten, straighten, square away [N. Amer], declutter

Derived forms: straightens out, straightening out, straightened out

Type of: alter, ameliorate, amend, better, change, clarify, clear up, elucidate, improve, meliorate, mend, modify, order

Antonym: mat