1. To temper
   "mitigating circumstances"
    
2. (law) lessen or to try to lessen the seriousness or extent of
   "The circumstances mitigate the crime";
   - extenuate, palliate

Derived forms: mitigated, mitigates, mitigating

Type of: decrease, excuse, lessen, minify, rationalise [Brit], rationalize

Encyclopedia: Mitigate