\Hem`e*ra*lo"pi*a\, n. [NL., fr. Gr. ?, the opposite
of ?; ? day + ? of ?. See {Nyctalopia}.] (Med.)
A disease of the eyes, in consequence of which a person can
see clearly or without pain only by daylight or a strong
artificial light; day sight.

Note: Some writers (as Quain) use the word in the opposite
      sense, i. e., day blindness. See {Nyctalopia}.