'Nyctalopia' definitions:

Definition of 'nyctalopia'

noun

Inability to see clearly in dim light; due to a deficiency of vitamin A or to a retinal disorder [syn: nyctalopia, night blindness, moon blindness]

From: GCIDE

Nyctalopia \Nyc`ta*lo"pi*a\ (n[i^]k`t[.a]*l[=o]"p[i^]*[.a]), n. [L. nyctalopia, fr. nyctalops a nyctalops, Gr. nykta`lwps. Gr. nykta`lwps meant, a person affected either with day blindness or with night blindness, and in the former case was derived fr. ny`x, nykto`s, night + 'w`ps, 'wpo`s, the eye; in the latter, fr. ny`x + 'alao`s blind + 'w`ps.] (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. [1913 Webster]
Note: Some writers (as Quain) use the word in the opposite sense, night blindness. See Hemeralopia. [1913 Webster]

From: GCIDE

Moonblink \Moon"blink`\, n. A temporary blindness, or impairment of sight, said to be caused by sleeping in the moonlight; -- sometimes called nyctalopia. [1913 Webster]