noun: Initialism of red, green, blue. (the colors output by a typical cathode-ray tube (i.e. an old computer monitor) used in varying combinations to render all colors) [(countable and uncountable) Any of a range of colours having the longest wavelengths, 670 nm, of the visible spectrum; a primary additive colour for transmitted light: the colour obtained by subtracting green and blue from white light using magenta and yellow filters; the colour of blood, ripe strawberries, etc.]