preoccupied

Short definition from Wiktionary

Adjective

1. 1
   Prepossessed; biased.
2. 2
   Already occupied.
3. 3
   Describing a taxonomic name not available for use because it is already used for another.
4. 4
   Concerned with something else; distracted; giving one's attention elsewhere.

Verb

1. 1
   simple past and past participle of preoccupy