Dictionary:

coloring

  (kŭl'ər-ĭng)

1. The art, manner, or process of applying color.
2. A substance used to color something.
3. Appearance with regard to color.
4. Characteristic aspect, tone, or style.
5. False or misleading appearance.

noun

1. Something that imparts color: color, colorant, dye, dyestuff, pigment, stain, tincture. See colors/colorless.
2. Skin tone, especially of the face: color, complexion. See colors/colorless.
3. A deceptive outward appearance: cloak, color, cover, disguise, disguisement, façade, face, false colors, front, gloss, guise, mask, masquerade, pretense, pretext, semblance, show, veil, veneer, window-dressing. Slang put-on. See show/hide.

The noun has 3 meanings:

Meaning #1: a digestible substance used to give color to food
  Synonyms: colouring, food coloring, food colouring, food color, food colour

Meaning #2: a visual attribute of things that results from the light they emit or transmit or reflect
  Synonyms: color, colour, colouring

Meaning #3: the act or process of changing the color of something
  Synonym: colouring