Monochromatic

adj. of one color; of one wavelength

Monochrome comes from the two Greek words mono (μoνο, meaning "only" or "alone"), and chroma (χρωμα, meaning "colour"). A monochromatic object has a single colour.In physics, the word is used more generally to refer to electromagnetic radiation of a single wavelength. In the physical sense, no real source of electromagnetic radiation is purely monochromatic, since that would require a wave of infinite duration. Even sources such as lasers have some narrow range of wavelengths (known as the linewidth or bandwidth of the source) within which they operate. In practice, filtered light, diffraction grating separated light and laser light are all routinely referred to as monochromatic. Often light sources can be compared and one be labeled as "more monochromatic" (in a similar usage as monodispersity). And a device which isolates light sources of a narrow bandwidth are called monochromators, even though the bandwidth is often explicitly specified, and thus a collection of wavelengths is understood.
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Adjective
1. of or relating to monochromatism
(pertainym) monochromacy, monochromatism, monochromatic vision, monochromia, monochromasy
2. (of light or other electromagnetic radiation) having only one wavelength; "monochromatic light"
(synonym) homochromatic
(antonym) polychromatic
3. having or appearing to have only one color
(synonym) monochrome, monochromic, monochromous
(similar) colored, coloured, colorful

(a.)
Consisting of one color, or presenting rays of light of one color only.
  

In optics, pertaining to a single wavelength of electromagnetic radiation or to a single color. Note: In practice, optical radiation is never perfectly monochromatic, i.e. , it never consists of only one wavelength. It always has a finite spectral width, albeit narrow.