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®

lonesome
     adj 1: being the only one; single and isolated from others; "the
            lone doctor in the entire county"; "a lonesome pine";
            "an only child"; "the sole heir"; "the sole example";
            "a solitary instance of cowardice"; "a solitary speck
            in the sky" [syn: {lone(a)}, {lonesome(a)}, {only(a)},
             {sole(a)}, {solitary(a)}]
     2: marked by dejection from being alone; "felt sad and lonely";
        "the loneliest night of the week"; "lonesome when her
        husband is away"; "spent a lonesome hour in the bar" [syn:
         {lonely}]