What is the meaning of preoccupied?

verb

• Engage or engross the interest or attention of beforehand or occupy urgently or obsessively.
  • usage: "His work preoccupies him"; "The matter preoccupies her completely-she cannot think of anything else"
  • synonyms: preoccupy
• Occupy or take possession of beforehand or before another or appropriate for use in advance.
  • usage: "the army preoccupied the hills"
  • synonyms: preoccupy

adjective

• Deeply absorbed in thought.
  • usage: "as distant and bemused as a professor listening to the prattling of his freshman class"; "lost in thought"; "a preoccupied frown"
  • synonyms: bemused, deep in thought, lost
• Having or showing excessive or compulsive concern with something.
  • usage: "became more and more haunted by the stupid riddle"; "was absolutely obsessed with the girl"; "got no help from his wife who was preoccupied with the children"; "he was taken up in worry for the old woman"
  • synonyms: haunted, obsessed, taken up