Monochromatic \Mon`o*chro*mat"ic\, a. [Cf. F. monochromatique. See Monochrome.]

Consisting of one color, or presenting rays of light of one color only.

Monochromatic lamp (Opt.),a lamp whose flame yields rays of some one homogenous light. It is of great importance in optical experiments.

Source: Webster's Revised Unabridged Dictionary (1913)