Cyan (/ˈs.ən/ or /ˈs.æn/) is a greenish-blue color. On the color wheels of the RGB (additive) and CMYK (subtractive) color models, it is located midway between blue and green, making it the complementary color of red.

Its name is derived from the Ancient Greek κυανός, transliterated kýanos, meaning "dark blue". It was formerly known as "cyan blue" or cyan-blue, and its first recorded use of as a color name in English was in 1879. Further origins of the color name can be traced back to a dye produced from the cornflower (Centaurea cyanus).

The web color cyan is synonymous with aqua. In most languages, 'cyan' is not a basic color term and it phenomenologically appears as a greenish vibrant hue of blue to most English speakers. Reasons for why cyan is not linguistically acknowledged as a basic color term can be found in the frequent lack of distinction between blue and green in many languages. Some varieties in the cyan color range are teal, turquoise, electric blue, aquamarine, and other colors described as blue-green.

In the CMYK color model, used in color printing, cyan is one of the primary colors, along with magenta, yellow, and black, which can be overlaid to produce all colors in the CMYK color model. In the additive color system, or RGB color model, used to create all the colors on a computer or television display, cyan is made by mixing equal amounts of green and blue light. Since it is the complement of red, it can also be made by the removal of red from white light. Mixing red light and cyan light at the right intensity on a black screen will make white. Cyan light has a wavelength of between 490 and 520 nanometers, between the wavelengths of blue and green.

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Carl Sagan
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