Synonyms for Monochromatic (same or very similar meaning)
WordNet sense 1 (having or appearing to have only one color):
monochrome, monochromic, monochromous
WordNet sense 2 (having color or a certain color; sometimes used in combination):
colored, colorful, coloured
WordNet sense 3 ((of light or other electromagnetic radiation) having only one wavelength):
homochromatic
From the ODE community, based on WordNet
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