These words describe persons whose complete attention is held or whose total concern is aroused by a particular subject. Preoccupied points to a mind taken up with a certain line of thought to the exclusion of other matters which might be competing for attention. It may suggest a dedicated and voluntary concern for something: preoccupied with details of the merger plan. More often I suggests an excessive or involuntary brooding about something; so preoccupied with his career that he was neglectful of his family; indications that thoughts of suicide had preoccupied him for months. The word may also simply suggest a mind lost in haphazard thought of any kind whatsoever and, consequently, inattentive to the matter at hand: a clerk who met my question with a vacant and preoccupied stare.

Involved pertains to commitment more than to concern, and it can be used for active behaviour as well as for mental states: students involved in the anti-conscription campaign; readers who can become deeply involved in the plot of a mystery thriller.

Absorbed and engrossed contrast with preoccupied in being almost wholly positive in connotation. Both these words refer primarily to a voluntary, almost eager, attentiveness to, or interest in, something. Engrossed suggests complete and alert intellectual concentration: engrossed in studying the committee’s findings. Absorbed may suggest an emotional interest that is even more complete: utterly absorbed by the film’s slow unfolding. Absorbed , furthermore, may suggest an intensity of interest in one’s own activity; so absorbed in his own story that he failed to notice the growing restlessness among his listeners.