monochromatic

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Having or appearing to have only one color.
• adjective Of or composed of radiation of only one wavelength.
• adjective Done in monochrome.
• adjective Exhibiting monochromatism.
• adjective Unvarying or dull.

from The Century Dictionary.

• Consisting of light of one wave-length, and in that sense of one color only, as the light produced by a Bunsen flame in which sodium is being volatilized.
• In psychology, pertaining to or characterized by monochromasy: as, monochromatic vision.
• Having an affinity for only one dye at a time, in contradistinction to polychromatic.
• noun Same as monochromate, 2.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Consisting of one color, or presenting rays of light of one color only.
• adjective (Opt.) a lamp whose flame yields rays of some one homogenous light. It is of great importance in optical experiments.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Having only one color, represented by differing hues and tints. For example shades in a black and white television.
• adjective Perceptive of only one color; unable to distinguish colors; total color blindness.
• adjective figuratively Plain, dull, lifeless.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective (of light or other electromagnetic radiation) having only one wavelength
• adjective having or appearing to have only one color
• adjective of or relating to monochromatism