discolouration

/D IH0 S K AH1 L ER0 EY1 SH AH0 N/
noun
  1. 1

    The act of discoloring, or the state of being discolored; alteration of hue or appearance.

  2. 2

    A discolored spot; a stain.

Source: https://en.wiktionary.org/wiki/discoloration, https://en.wiktionary.org/wiki/discolouration