WordWeb Online

1. Lessen the density or solidity of
   "The bones are rarefied";
   - rarify [rare]
    
2. Make more subtle or refined
   - sublimate, subtilize, rarify [rare], subtilise [Brit]
    
3. (chemistry) weaken the consistency of (a chemical substance)
   - attenuate, rarify [rare]
    
4. Make more complex, intricate, or rich
   - complicate, refine, rarify [rare], elaborate

Derived forms: rarefying, rarefies, rarefied

Type of: alter, change, modify, weaken

Encyclopedia: Rarefy