definition of
colouring

[1] #1 colouring n. [coloring, food coloring, food colouring, food color, food colour] a digestible substance used to give color to food; "food color made from vegetable dyes". wn

[2] #2 colouring n. [color, colour, coloring] a visual attribute of things that results from the light they emit or transmit or reflect; "a white color is made up of many different wavelengths of light". wn

[3] #3 colouring n. [coloring] the act or process of changing the color of something. wn