Source : Webster's Revised Unabridged Dictionary (1913)

Twilight \Twi"light`\, a.
   1. Seen or done by twilight. --Milton.

   2. Imperfectly illuminated; shaded; obscure.

            O'er the twilight groves and dusky caves. --Pope.

Twilight \Twi"light`\, n. [OE. twilight, AS. twi- (see {Twice})
   + le['o]ht light; hence the sense of doubtful or half light;
   cf. LG. twelecht, G. zwielicht. See {Light}.]
   1. The light perceived before the rising, and after the
      setting, of the sun, or when the sun is less than 18[deg]
      below the horizon, occasioned by the illumination of the
      earth's atmosphere by the direct rays of the sun and their
      reflection on the earth.

   2. faint light; a dubious or uncertain medium through which
      anything is viewed.

            As when the sun . . . from behind the moon, In dim
            eclipse, disastrous twilight sheds.   --Milton.

            The twilight of probability.          --Locke.

Source : WordNet®

twilight
     adj : lighted by or as if by twilight; "The dusky night rides down
           the sky/And ushers in the morn"-Henry Fielding; "the
           twilight glow of the sky"; "a boat on a twilit river"
           [syn: {dusky}, {twilight(a)}, {twilit}]
     n 1: the time of day immediately following sunset; "he loved the
          twilight"; "they finished before the fall of night"
          [syn: {dusk}, {gloaming}, {nightfall}, {evenfall}, {fall},
           {crepuscule}, {crepuscle}]
     2: the diffused light from the sky when the sun is below the
        horizon but its rays are refracted by the atmosphere of
        the earth
     3: a condition of decline following successes; "in the twilight
        of the empire"