Is it ensure, insure, or assure?
1807, from mono- + chromatic, or from monochrome + -atic. Related: Monochromatically (1784).
monochromatic mon·o·chro·mat·ic (mŏn'ə-krō-māt'ĭk)adj.
Having or appearing to have only one color.
Of or relating to a pure spectral color of a single wavelength.
Of or exhibiting achromatopsia.
Consisting of a single wavelength of light or other radiation. Lasers, for example, usually produce monochromatic light.
Having or appearing to have only one color. Compare polychromatic.