What is the meaning of Cyan?

An additive secondary colour midway between green and blue, evoked by wavelengths between ~490 and ~520 nm.

Of the colour cyan.

cyan

cyan (vibrant pale greenish-blue colour between blue and green in the visible spectrum)

cannot

cyan (colour)

cyan

Almost any chemical compound containing a cyanide group; especially if this compound is in gaseous state.

Source: wiktionary.org