Cerulean, also spelled caerulean, is a color term that may be applied to a wide range of colors from deep blue, sky-blue, bright blue or azure colors through blueish green colors.
The first recorded use of cerulean as a color name in English was in 1590. The word is probably derived from the Latin word caeruleus, "dark blue, blue or blue-green", which in turn probably derives from caelulum, diminutive of caelum, "heaven, sky".
Read more about Cerulean: Use in Artistic Painting, Cerulean Blue, Cerulean in Nature, Cerulean in Human Culture