Where Does Preoccupied Mean?

1 : previously applied to another group and unavailable for use in a new sense —used of a biological generic or specific name. 2a : lost in thought also : absorbed in some preoccupation. b : already occupied.

What does this mean preoccupied?

If you are preoccupied, you are thinking a lot about something or someone, and so you hardly notice other things.

Is it preoccupied or occupied?

As adjectives the difference between occupied and preoccupied is that occupied is "reserved, engaged" while preoccupied is "concerned with something else; distracted; giving one's attention elsewhere".