WordWeb Online

1. Lose color or turn colorless
   "The painting discolored";
   - discolour [Brit, Cdn]
    
2. Cause to lose or change color
   "The detergent discolored my shirts";
   - discolour [Brit, Cdn]
    
3. Change color, often in an undesired manner
   "The shirts discolored";
   - discolour [Brit, Cdn], colour [Brit, Cdn], color [US]

Derived forms: discoloring, discolored, discolors

Type of: alter, change, modify

Antonym: colorise [Brit]