Cyan ( /ˈsaɪ.ən/ or /ˈsaɪ.æn/; from Greek: κύανoς, transliterated: kýanos, meaning "dark blue substance") may be used as the name of any of a number of colors in the blue/green range of the spectrum. In reference to the visible spectrum cyan is used to refer to the color obtained by mixing equal amounts of green and blue light or the removal of red from white light. As such, cyan is the complement of red in RGB and CMYK color models: cyan pigments absorb red light.

Cyan is also called aqua or blue-green, and was formerly known as "cyan blue".

The first recorded use of cyan blue (as noted above, "cyan blue" was the name used for the color "cyan" in the 19th century) as a color name in English was in 1879.

Some tones of color close to cyan in the cyan color range are teal, turquoise, electric blue and aquamarine.