The visual appearance or shade of something; the act of adding color; substances used to color things, particularly food.
From Old French 'colour', ultimately from Latin 'color'. The British spelling 'colouring' (American 'coloring') adds the gerund suffix '-ing' to create a noun describing both the process and result.
Food colouring went from plant dyes that were dangerous and unpredictable to synthetic versions—the word stayed the same while what it meant became a chemistry experiment.
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