Source : Webster's Revised Unabridged Dictionary (1913)

Lonesome \Lone"some\, a. [Compar. {Lonesomer}; superl.
   {Lonesomest}.]
   1. Secluded from society; not frequented by human beings;
      solitary.

            Like one that on a lonesome road Doth walk in fear
            and dread.                            --Coleridge.

   2. Conscious of, and somewhat depressed by, solitude; as, to
      feel lonesome. -- {Lone"some*ly}, adv. --
      {Lone"some*ness}, n.

Source : WordNet®

lonesomeness
     n : a disposition toward being alone [syn: {aloneness}, {loneliness},
          {solitude}]