The color of light with wavelengths of roughly 450–495 nanometers, the shortest of the three additive primary colors.
Under Rayleigh scattering, violetlight scatters more than blue because shorter wavelengths scatter more. Yet the sky looks blue, not violet: the sun emits little violet light, and our blue cones are much more sensitive than violet ones.
A giraffe's tongue reaches 45–53 cm with a tip colored deep blue, black, or purple. The dark hue comes from melanin, and the leading explanation is ultraviolet protection: giraffes spend 16–20 hours browsing with the tongue out, so its most exposed part needs sunscreen.