Chartreuse as a colour name comes from the yellow-green liqueur produced by Carthusian monks at the Grande Chartreuse monastery near Grenoble, France. The monks have made the liqueur since 1737 from a recipe supposedly given to them in 1605 — only two monks know the complete formula at any time. The colour of the yellow variant became "chartreuse" in English usage.

Acid, electric, and slightly aggressive. Chartreuse is the most visually demanding of all colours — it sits at the peak of the human eye's luminosity sensitivity and simultaneously activates both red and green colour receptors. This dual activation creates a colour that is almost impossible to ignore. Associated with energy drinks, safety vests, and the particular vibrancy of new spring growth.

The human eye is most sensitive to yellow-green light — the peak of the photopic luminosity function falls at approximately 555nm, very close to chartreuse. This is why safety vests, emergency vehicles, and high-visibility clothing use this colour range. The Carthusian monks have been making their yellow-green liqueur for nearly 300 years — a remarkable continuity of both recipe and colour. The monastery was nationalised during the French Revolution but the monks eventually recovered it.