1. The act of changing the natural colour of something by making it duller, dingier, unnatural or faded
   "The discolouration of the old photograph made it difficult to recognize the people in it";
   - discoloration
    
2. A soiled or discoloured appearance
   "the wine left a dark discolouration";
   - stain, discoloration

Derived forms: discolourations

Type of: appearance, change of color [US], change of colour [Brit, Cdn], visual aspect