engage or engross the interest or attention of beforehand or occupy urgently or obsessively; "His work preoccupies him"; "The matter preoccupies her completley--she cannot think of anything else"
occupy or take possession of beforehand or before another or appropriate for use in advance; "the army preoccupied the hills"
To prepossess; to engage, occupy, or engross the attention of, beforehand; hence, to prejudice
To take possession of before another; as, to preoccupy a country not before held
If something is preoccupying you, you are thinking about it a lot. Crime and the fear of crime preoccupy the community. if something preoccupies someone, they think or worry about it a lot