Wiktionary
n. (alternative spelling of primary colour English)
Wikipedia
Primary colors are sets of colors that can be combined to make a useful range of colors. For human applications, three primary colors are typically used, since human color vision is usually trichromatic.
For additive combination of colors, as in overlapping projected lights or in electronic visual displays, the primary colors normally used are red, green and blue. For a subtractive combination of colors, as in mixing of pigments or dyes for printing, the colors magenta, yellow and cyan are normally used. However, red, yellow and blue are commonly used as primaries when painting or drawing. See RGB color model, CMYK color model and RYB color model for more on these popular sets of primary colors.
In an additive system, choices of sets of primary colors are nearly arbitrary, subject to weak constraints from the spectral sensitivities of each of the human cone photoreceptors. An early color photographic process, autochrome, typically used orange, green and violet primaries. However, unless negative amounts of a color are allowed, the gamut will be restricted to the color triangle defined by the choice of primaries.
The combination of any two primary colors creates a secondary color. The most commonly used additive color primaries are the secondary colors of the most commonly used subtractive color primaries, and vice versa.
Usage examples of "primary color".
Nearly all of them were geometric solids of one sort or another: cubes, cones, dodecahedrons, oblate spheroids, three-, four-, and five-sided pyramids, each painted or coated in a bright primary color.
It was like seeing a color you've never seen before, a new primary color.
Inside, the primary color on the standing walls was the rusty red of dried blood.
It was like trying to visualize a new primary color or a world in which you could recognize several hundred acquaintances individually only by their smells.
He'd had a harper drawer make up a huge map of Pern, the seas in the bright primary color the dolphins could recognize as sea' as opposed to the dark' landmasses.