Loneliness

from WordNet (r) 3.0 (2006)

loneliness
    n 1: the state of being alone in solitary isolation [syn:
         {loneliness}, {solitariness}]
    2: sadness resulting from being forsaken or abandoned [syn:
       {forlornness}, {loneliness}, {desolation}]
    3: a disposition toward being alone [syn: {aloneness},
       {loneliness}, {lonesomeness}, {solitariness}]

from The Collaborative International Dictionary of English v.0.48

Loneliness \Lone"li*ness\, n.
   1. The condition of being lonely; solitude; seclusion.
      [1913 Webster]

   2. The state of being unfrequented by human beings; as, the
      loneliness of a road.
      [1913 Webster]

   3. Love of retirement; disposition to solitude.
      [1913 Webster]

            I see
            The mystery of your loneliness.       --Shak.
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   4. A feeling of depression resulting from being alone.
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   Syn: Solitude; seclusion. See {Solitude}.
        [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

20 Moby Thesaurus words for "loneliness":
      alienation, aloneness, aloofness, celibacy, detachment, isolation,
      keeping apart, loneness, lonesomeness, moving apart, privacy,
      seclusion, separateness, sequestration, single blessedness,
      singleness, solitariness, solitude, splendid isolation,
      withdrawal