Source : Webster's Revised Unabridged Dictionary (1913)

Congressional \Con*gres"sion*al\, a.
   Of or pertaining to a congress, especially, to the Congress
   of the United States; as, congressional debates.

         Congressional and official labor.        --E. Everett.

   {Congressional District}, one of the divisions into which a
      State is periodically divided (according to population),
      each of which is entitled to elect a Representative to the
      Congress of the United States.

Source : WordNet®

congressional district
     n : a territorial division of a state; entitled to elect one
         member to the United States House of Representatives