Wikipedia
Red-violet is a rich color of high medium saturation about 3/4 of the way between red and magenta, closer to magenta than to red. It is classified in color theory as one of the purple colors—a non- spectral color between red and violet that is a deep version of a color on the line of purples on the CIE chromaticity diagram. Both its saturation and brightness falling short of 100%, red-violet is not a pure chroma. There is a color of similar hue that, however, comes close to being a pure chroma: process magenta. The pure chroma color composed of equal parts of magenta and red is called rose.
In the use by artists, red-violet is equivalent to purple, however, although the color " purple" is inaccurately used by many people as a synonym for violet or a color close to violet, professional artists who use the RYB color wheel generally use the term "purple" to specifically refer to a pigment color that is equivalent to red-violet (i.e., the tertiary color between violet and red on the RYB color wheel) in order to give themselves a larger and more balanced palette of pigments to work with.
The Munsell color system also refers to red-violet as purple; in the Munsell color system, this color at the maximum chroma of 12 is called Red-Purple. This convention is for chromatic purposes, since Red-Purple lies between violet and printer's magenta (the color regarded as magenta before the invention of the color electric magenta for computer displays).