nyctalopia Meaning, Definition & Usage

  1. noun inability to see clearly in dim light; due to a deficiency of vitamin A or to a retinal disorder
    night blindness; moon blindness.

WordNet

Nyc`ta*lo"pi*a noun
Etymology
L. nyctalopia, fr. nyctalops a nyctalops, Gr. . Gr. meant, a person affected either with day blindness or with night blindness, and in the former case was derived fr. , , night + , , the eye; in the latter, fr. + blind + .
Definitions
  1. (Med.) (a) A disease of the eye, in consequence of which the patient can see well in a faint light or at twilight, but is unable to see during the day or in a strong light; day blindness. (b) See Moonblink. ✍ Some writers (as Quain) use the word in the opposite sense, night blindness. See Hemeralopia.

Webster 1913