Wordnet 3.0
ADJECTIVE (1)
1. 
 affected or marked by low spirits; 
- Example: "is dejected but trying to look cheerful"
The Collaborative International Dictionary of English v.0.48:
Deject \De*ject"\, v. t. [imp. & p. p. Dejected; p. pr. & vb.
   n. Dejecting.] [L. dejectus, p. p. of dejicere to throw
   down; de- + jacere to throw. See Jet a shooting forth.]
   1. To cast down. [Obs. or Archaic]
      [1913 Webster]
            Christ dejected himself even unto the hells.
                                                  --Udall.
      [1913 Webster]
            Sometimes she dejects her eyes in a seeming
            civility; and many mistake in her a cunning for a
            modest look.                          --Fuller.
      [1913 Webster]
   2. To cast down the spirits of; to dispirit; to discourage;
      to dishearten.
      [1913 Webster]
            Nor think, to die dejects my lofty mind. --Pope.
      [1913 Webster]
The Collaborative International Dictionary of English v.0.48:
Dejected \De*ject"ed\, a.
   Cast down; afflicted; low-spirited; sad; as, a dejected look
   or countenance. -- De*ject"ed*ly, adv. --
   De*ject"ed*ness, n.
   [1913 Webster]
WordNet (r) 3.0 (2006):
dejected
    adj 1: affected or marked by low spirits; "is dejected but
           trying to look cheerful" [ant: elated]
Moby Thesaurus II by Grady Ward, 1.0:
68 Moby Thesaurus words for "dejected":
   beetle-browed, black, black-browed, blue, bowed-down, cast down,
   crestfallen, dark, dashed, depressed, despairing, despondent,
   desponding, disconsolate, discouraged, disheartened, dispirited,
   dour, down, downcast, downhearted, drooping, droopy, dumpish,
   feeling low, forlorn, frowning, gloomy, glowering, glum, grim,
   grum, heartbroken, heartless, hypochondriac, hypochondriacal,
   in low spirits, in the depths, in the doldrums, in the dumps,
   languishing, low, low-spirited, lowering, melancholy, miserable,
   moodish, moody, mopey, moping, mopish, morose, mumpish,
   pessimistic, pining, sad, scowling, sorrowful, spiritless, subdued,
   suicidal, sulky, sullen, surly, unhappy, weary of life, woebegone,
   world-weary