‖n. [ NL., fr. Gr. &unr_;, the opposite of &unr_;; &unr_; day + &unr_; of &unr_;. 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. [ 1913 Webster ]

☞ Some writers (as Quain) use the word in the opposite sense, i. e., day blindness. See Nyctalopia. [ 1913 Webster ]