ETYM Written also colour.
1. A visual attribute of things that results from the light they emit or transmit or reflect; SYN. colour, coloring, colouring.
2. Interest and variety and intensity; SYN. colour, vividness.
3. The timbre of a musical sound; SYN. colour.
4. A race with skin pigmentation different from the white race (especially Blacks); SYN. colour, people of color, people of colour.

1. To add color to; SYN. colour, color in, colour in.
2. To add color to.
3. To decorate with colors; SYN. colour, emblazon.
4. To distort; SYN. distort.
5. To gloss or excuse; SYN. gloss.
6. To modify or bias.

(Photography) Displaying more colors than black and white; SYN. colour.

Quality or wavelength of light emitted or reflected from an object. Visible white light consists of electromagnetic radiation of various wavelengths, and if a beam is refracted through a prism, it can be spread out into a spectrum, in which the various colors correspond to different wavelengths. From long to short wavelengths (from about 700 to 400 nanometers) the colors are red, orange, yellow, green, blue, indigo, and violet.
The light entering our eyes is either reflected from the objects we see, or emitted by hot or luminous objects. Sources of light have a characteristic spectrum or range of wavelengths. Hot solid objects emit light with a broad range of wavelengths, the maximum intensity being at a wavelength which depends on the temperature. The hotter the object, the shorter the wavelengths emitted, as described by Wien's law. Hot gases, such as the vapor of sodium street lights, emit light at discrete wavelengths. The pattern of wavelengths emitted is unique to each gas and can be used to identify the gas (see spectroscopy).
When an object is illuminated by white light, some of the wavelengths are absorbed and some are reflected to the eye of an observer. The object appears colored because of the mixture of wavelengths in the reflected light. For instance, a red object absorbs all wavelengths falling on it except those in the red end of the spectrum. This process of subtraction also explains why certain mixtures of paints produce different colors. Blue and yellow paints when mixed together produce green because between them the yellow and blue pigments absorb all wavelengths except those around green. A suitable combination of three pigments—cyan (blue–green), magenta (blue–red), and yellow—can produce any color when mixed. This fact is used in color printing, although additional black pigment is also added.
In the light-sensitive lining of our eyeball (the retina), cells called cones are responsible for color vision. There are three kinds of cones. Each type is sensitive to one color only, either red, green, or blue. The brain combines the signals sent from the set of cones to produce a sensation of color. When all cones are stimulated equally the sensation is of white light. The three colors to which the cones respond are called the primary colors. By mixing lights of these three colors it is possible to produce any color. This process is called color mixing by addition, and is used to produce the color on a television screen where glowing phosphor dots of red, green, and blue combine. Pairs of colors that produce white light, such as orange and blue, are called complementary colors.
Many schemes have been proposed for classifying colors. The most widely used is the Munsell scheme, which classifies colors according to their hue (dominant wavelength), saturation (the degree of whiteness), and brightness (intensity).

In music, the quality or timbre of an instrument or voice. A “dark” sound denotes a thick, heavy sonority while a “light” sound describes a thinner, more transparent sonority. Alexander Skryabin invented a keyboard which would project colors on to a screen in order to reflect the mood and character of the music.

In physics, the component of the human perception of light that depends on frequency. For light of a single frequency, color ranges from violet at the high-frequency end of the visible-light band (a small portion of the total electromagnetic spectrum) to red at the low-frequency end. In computer video, color is produced by a combination of hardware and software. Software manipulates combinations of bits that represent the distinct shades of color that are destined for particular positions on the screen (characters or individual dots, called pixels). The video adapter hardware translates these bits into electrical signals, which in turn control the brightnesses of different-colored phosphors at the corresponding positions on the screen of the monitor CRT. The user’s eye unites the light from the phosphors to perceive a single color. See also color model, color monitor, CRT, HSB, monitor, RGB, video, video adapter.