D defs.my
Entry 1 sense Webster, 1913

coherent light

· co·her·ent light · IPA
01 n. Light in which the phases of all electromagnetic waves at each point on a line normal to the direction of the the beam are identical. Cohe…
  1. 1.
    Light in which the phases of all electromagnetic waves at each point on a line normal to the direction of the the beam are identical. Coherent light is usually monochromatic, and the most common source of such light for practical uses is from a laser.(Physics, Optics)