Definition of colouring matter in US English:

colouring matter

(US coloring matter)

noun

  • A substance to which the colour of a natural substance or object is due, or which is used to impart colour in a manufacturing or artistic procedure; a pigment, a dye.

Origin

Late 17th century; earliest use found in William Salmon (1644–1713), medical empiric and author. Partly (probably originally) from colouring + matter, and partly from colouring + matter; compare discussion at -ing.

Pronunciation

colouring matter

/ˈkʌl(ə)rɪŋ ˌmatə/