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"
occupy or take possession of beforehand or before another or appropriate for use in advance; "the army preoccupied the hills"
a hidden storage space (for money or provisions or weapons)
(computer science) RAM memory that is set aside as a specialized buffer storage that is continually updated; used to optimize data transfers between system elements with different characteristics