WordWeb Online

1. Being the only one; single and isolated from others
   "a lonesome pine"
   - lone, only, sole, solitary
    
2. Marked by dejection from being alone
   "lonesome when her husband is away"; "spent a lonesome hour in the bar"
   - lonely

See also: dejected, lonesomeness, single

Encyclopedia: Lonesome Lonesome, On'ry and Mean