primary color

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A color belonging to any of three groups each of which is regarded as generating all colors, with the groups being.
• noun Additive, physiological, or light primaries red, green, and blue. Lights of red, green, and blue wavelengths may be mixed to produce all colors.
• noun Subtractive or colorant primaries magenta, yellow, and cyan. Substances that reflect light of one of these wavelengths and absorb other wavelengths may be mixed to produce all colors.
• noun Psychological primaries red, yellow, green, and blue, plus the achromatic pair black and white. All colors may be subjectively conceived as mixtures of these.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Alternative spelling of primary colour.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any of three colors from which all others can be obtained by mixing