WordWeb Online

1. Having or showing excessive or compulsive concern with something
   "was absolutely obsessed with the girl";
   - haunted, preoccupied, taken up
    
2. Influenced or controlled by a powerful force such as a strong emotion
   "by love obsessed";
   - possessed

1. Haunt like a ghost; pursue
   "Fear of illness obsesses her";
   - haunt, ghost
    
2. Be preoccupied with something
   "She is obsessing over her weight"

See also: concerned, controlled

Type of: preoccupy, sweat [N. Amer, informal], worry

Encyclopedia: Obsessed