The Collaborative International Dictionary of English v.0.48:

Gloaming \Gloam"ing\, n. [See Gloom.]
   1. Twilight; dusk; the fall of the evening. [Scot. & North of
      Eng., and in poetry.] --Hogg.
      [1913 Webster]

   2. Sullenness; melancholy. [Obs.] --J. Still.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gloaming
    n 1: the time of day immediately following sunset; "he loved the
         twilight"; "they finished before the fall of night" [syn:
         twilight, dusk, gloaming, gloam, nightfall,
         evenfall, fall, crepuscule, crepuscle]