The Collaborative International Dictionary of English v.0.48:

night-sight \night-sight\ n.
   The ability to see in reduced illumination (as in moonlight);
   night vision.

   Syn: night vision.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

night-sight
    n 1: the ability to see in reduced illumination (as in
         moonlight) [syn: night vision, night-sight, scotopic
         vision, twilight vision]