Preoccupation is a state of being so absorbed in thinking about something that it's hard to focus on anything else. When you have a preoccupation, one particular thought or worry dominates your mind, crowding out other concerns.

Someone might have a preoccupation with an upcoming violin recital, replaying the difficult passages in their head during math class and at the dinner table. A scientist might have a preoccupation with solving a particular problem, thinking about it constantly even while doing other tasks. The word suggests more than casual interest: it means something has taken over a significant portion of your mental space.

Preoccupations can be productive or unproductive. A chess player's preoccupation with strategy might help them improve their game. But a preoccupation with something embarrassing that happened last week might just make you miserable without helping you move forward.

When someone seems distracted or distant, they might be dealing with a preoccupation that's commanding their attention, making it difficult to be fully present in the moment.