Source : Webster's Revised Unabridged Dictionary (1913)

Curtain \Cur"tain\, v. t. [imp. & p. p. {Curtained} (-t?nd; 48);
   p. pr. & vb. n. {Curtaining}.]
   To inclose as with curtains; to furnish with curtains.

         So when the sun in bed Curtained with cloudy red.
                                                  --Milton.

Source : WordNet®

curtained
     adj : furnished or concealed with curtains or draperies; "a
           curtained alcove" [ant: {curtainless}]