The Collaborative International Dictionary of English v.0.48:

Commerce \Com*merce"\ (? or ?), v. i. [imp. & p. p. Commerced;
   p. pr. & vb. n. Commercing.] [Cf. F. commercer, fr. LL.
   commerciare.]
   1. To carry on trade; to traffic. [Obs.]
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            Beware you commerce not with bankrupts. --B. Jonson.
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   2. To hold intercourse; to commune. --Milton.
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            Commercing with himself.              --Tennyson.
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            Musicians . . . taught the people in angelic
            harmonies to commerce with heaven.    --Prof.
                                                  Wilson.
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The Collaborative International Dictionary of English v.0.48:

Commerce \Com"merce\, n.

   Note: (Formerly accented on the second syllable.) [F.
         commerce, L. commercium; com- + merx, mercis,
         merchandise. See Merchant.]
   1. The exchange or buying and selling of commodities; esp.
      the exchange of merchandise, on a large scale, between
      different places or communities; extended trade or
      traffic.
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            The public becomes powerful in proportion to the
            opulence and extensive commerce of private men.
                                                  --Hume.
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   2. Social intercourse; the dealings of one person or class in
      society with another; familiarity.
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            Fifteen years of thought, observation, and commerce
            with the world had made him [Bunyan] wiser.
                                                  --Macaulay.
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   3. Sexual intercourse. --W. Montagu.
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   4. A round game at cards, in which the cards are subject to
      exchange, barter, or trade. --Hoyle.
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   Chamber of commerce. See Chamber.

   Syn: Trade; traffic; dealings; intercourse; interchange;
        communion; communication.
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WordNet (r) 3.0 (2006):

commerce
    n 1: transactions (sales and purchases) having the objective of
         supplying commodities (goods and services) [syn:
         commerce, commercialism, mercantilism]
    2: the United States federal department that promotes and
       administers domestic and foreign trade (including management
       of the census and the patent office); created in 1913 [syn:
       Department of Commerce, Commerce Department, Commerce,
       DoC]
    3: social exchange, especially of opinions, attitudes, etc.

The Devil's Dictionary (1881-1906):

COMMERCE, n.  A kind of transaction in which A plunders from B the
goods of C, and for compensation B picks the pocket of D of money
belonging to E.