Definition of: nyctalopia

(nik′tə·lō′pē·ə) noun Pathol.
Night blindness; a physical defect of the eyes in which one sees well by daylight, but poorly in the dark or in dim light: sometimes confused with day blindness or hemeralopia. Also nyc′ta·lo′py. [<NL <Gk. nyx, nyktos night + alaos blind + ōps eye]
—nyc′ta·lop′ic (-lop′·ik) adjective