discolour
verb(US English discolor)
[intransitive, transitive]to change colour, or to make the colour of something change, in a way that makes it look less attractive （使）变色，退色 Plastic tends to discolour with age. 塑料久而久之便会退色。 - discolour something
The pipes were beginning to rust, discolouring the water. 管子开始生锈，水都变颜色了。
Word Originlate Middle English: from Old French descolorer or medieval Latin discolorare, from des-, dis- (expressing reversal) + Latin colorare ‘to colour’.