The Collaborative International Dictionary of English v.0.48:

Commercial \Com*mer"cial\, a. [Cf. F. commercial.]
   Of or pertaining to commerce; carrying on or occupied with
   commerce or trade; mercantile; as, commercial advantages;
   commercial relations. "Princely commercial houses."
   --Macaulay.
   [1913 Webster]

   Commercial college, a school for giving instruction in
      commercial knowledge and business.

   Commercial law. See under Law.

   Commercial note paper, a small size of writing paper,
      usually about 5 by 71/2 or 8 inches.

   Commercial paper, negotiable paper given in due course of
      business. It includes bills of exchange, promissory notes,
      bank checks, etc.

   Commercial traveler, an agent of a wholesale house who
      travels from town to town to solicit orders.

   Syn: See Mercantile.
        [1913 Webster]

WordNet (r) 3.0 (2006):

commercial traveler
    n 1: a salesman who travels to call on customers [syn:
         traveling salesman, travelling salesman, commercial
         traveler, commercial traveller, roadman, bagman]