In Latin, ashes are called cinis and , similarly, the Latin word for ashy gray or ash-like is cinereous. English borrowed this word in the 17th century and it has long been used to describe the color which is dark gray tinged with brown shininess. As with many Latin color names (like fulvous and icterine) the word cinereous is often used in the scientific name of birds which are very prone to be this drab color.
However, the concept of color is not quite as simple as it first seems. Different items produce ocular sensations as a result of the way they reflect or emit light, yet different wavelengths of light are visible to different eyes. Humans are trichromats. We have photoreceptor cells capable of seeing blue, green, and red. Most birds are tetrachromats and can apprehend electromagnetic wavelengths in the ultraviolet spectrum as well. Many of the dull cinereous birds we witness may glow and sparkle with colors unknown to the human eye and unnamed by the human tongue.