The Collaborative International Dictionary of English v.0.48:

Traffic \Traf"fic\, v. i. [imp. & p. p. Trafficked; p. pr. &
   vb. n. Trafficking.] [F. trafiquer; cf. It. trafficare, Sp.
   traficar, trafagar, Pg. traficar, trafegar, trafeguear, LL.
   traficare; of uncertain origin, perhaps fr. L. trans across,
   over + -ficare to make (see -fy, and cf. G. ["u]bermachen
   to transmit, send over, e. g., money, wares); or cf. Pg.
   trasfegar to pour out from one vessel into another, OPg.
   also, to traffic, perhaps fr. (assumed) LL. vicare to
   exchange, from L. vicis change (cf. Vicar).]
   1. To pass goods and commodities from one person to another
      for an equivalent in goods or money; to buy or sell goods;
      to barter; to trade.
      [1913 Webster]

   2. To trade meanly or mercenarily; to bargain.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "trafficking":
   agency, barter, bartering, brokerage, buying and selling, dealing,
   doing business, exchange, give-and-take, horse trading,
   interchange, jobbing, merchandising, retailing, swapping, trade,
   trading, wheeling and dealing, wholesaling