The Collaborative International Dictionary of English v.0.48:

Dusk \Dusk\, a. [OE. dusc, dosc, deosc; cf. dial. Sw. duska to
   drizzle, dusk a slight shower. ???.]
   Tending to darkness or blackness; moderately dark or black;
   dusky.
   [1913 Webster]

         A pathless desert, dusk with horrid shades. --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dusk \Dusk\, n.
   1. Imperfect obscurity; a middle degree between light and
      darkness; twilight; as, the dusk of the evening.
      [1913 Webster]

   2. A darkish color.
      [1913 Webster]

            Whose duck set off the whiteness of the skin.
                                                  --Dryden.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dusk \Dusk\, v. t.
   To make dusk. [Archaic]
   [1913 Webster]

         After the sun is up, that shadow which dusketh the
         light of the moon must needs be under the earth.
   --Holland.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dusk \Dusk\, v. i.
   To grow dusk. [R.] --Chaucer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dusk
    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]
    v 1: become dusk