The Collaborative International Dictionary of English v.0.48:

Gloam \Gloam\, n.
   The twilight; gloaming. [R.] --Keats.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gloam \Gloam\, v. i. [See Gloom, Glum.]
   [1913 Webster]
   1. To begin to grow dark; to grow dusky.
      [1913 Webster]

   2. To be sullen or morose. [Obs.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

gloam
    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]