Source : Webster's Revised Unabridged Dictionary (1913)

Preoccupation \Pre*oc`cu*pa"tion\, n. [L. praeoccupatio: cf. F.
   pr['e]occupation.]
   1. The act of preoccupying, or taking possession of
      beforehand; the state of being preoccupied; prepossession.

   2. Anticipation of objections. [R.] --South.

Source : WordNet®

preoccupation
     n 1: an idea that preoccupies the mind and holds the attention
     2: the mental state of being preoccupied by something [syn: {preoccupancy},
         {absorption}, {engrossment}]
     3: the act of taking occupancy before someone else does [syn: {preoccupancy}]