S: (v) preoccupy (engage or engross the interest or attention of beforehand or occupy urgently or obsessively) "His work preoccupies him"; "The matter preoccupies her completely--she cannot think of anything else"
S: (v) haunt, obsess, ghost (haunt like a ghost; pursue) "Fear of illness haunts her"
S: (v) prepossess (cause to be preoccupied) "The idea of his failure prepossesses him"
W: (n) obsession [Related to: obsess] (an unhealthy and compulsive preoccupation with something or someone)
W: (n) ghost [Related to: ghost] (a mental representation of some haunting experience) "he looked like he had seen a ghost"; "it aroused specters from his past"