The Collaborative International Dictionary of English v.0.48:

Trade \Trade\, n. [Formerly, a path, OE. tred a footmark. See
   Tread, n. & v.]
   1. A track; a trail; a way; a path; also, passage; travel;
      resort. [Obs.]
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            A postern with a blind wicket there was,
            A common trade to pass through Priam's house.
                                                  --Surrey.
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            Hath tracted forth some salvage beastes trade.
                                                  --Spenser.
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            Or, I'll be buried in the king's highway,
            Some way of common trade, where subjects' feet
            May hourly trample on their sovereign's head.
                                                  --Shak.
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   2. Course; custom; practice; occupation; employment. [Obs.]
      "The right trade of religion." --Udall.
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            There those five sisters had continual trade.
                                                  --Spenser.
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            Long did I love this lady,
            Long was my travel, long my trade to win her.
                                                  --Massinger.
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            Thy sin's not accidental but a trade. --Shak.
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   3. Business of any kind; matter of mutual consideration;
      affair; dealing. [Obs.]
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            Have you any further trade with us?   --Shak.
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   4. Specifically: The act or business of exchanging
      commodities by barter, or by buying and selling for money;
      commerce; traffic; barter.
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   Note: Trade comprehends every species of exchange or dealing,
         either in the produce of land, in manufactures, in
         bills, or in money; but it is chiefly used to denote
         the barter or purchase and sale of goods, wares, and
         merchandise, either by wholesale or retail. Trade is
         either foreign or domestic. Foreign trade consists in
         the exportation and importation of goods, or the
         exchange of the commodities of different countries.
         Domestic, or home, trade is the exchange, or buying and
         selling, of goods within a country. Trade is also by
         the wholesale, that is, by the package or in large
         quantities, generally to be sold again, or it is by
         retail, or in small parcels. The carrying trade is the
         business of transporting commodities from one country
         to another, or between places in the same country, by
         land or water.
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   5. The business which a person has learned, and which he
      engages in, for procuring subsistence, or for profit;
      occupation; especially, mechanical employment as
      distinguished from the liberal arts, the learned
      professions, and agriculture; as, we speak of the trade of
      a smith, of a carpenter, or mason, but not now of the
      trade of a farmer, or a lawyer, or a physician.
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            Accursed usury was all his trade.     --Spenser.
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            The homely, slighted, shepherd's trade. --Milton.
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            I will instruct thee in my trade.     --Shak.
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   6. Instruments of any occupation. [Obs.]
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            The house and household goods, his trade of war.
                                                  --Dryden.
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   7. A company of men engaged in the same occupation; thus,
      booksellers and publishers speak of the customs of the
      trade, and are collectively designated as the trade.
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   8. pl. The trade winds.
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   9. Refuse or rubbish from a mine. [Prov. Eng.]
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   Syn: Profession; occupation; office; calling; avocation;
        employment; commerce; dealing; traffic.
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   Board of trade. See under Board.

   Trade dollar. See under Dollar.

   Trade price, the price at which goods are sold to members
      of the same trade, or by wholesale dealers to retailers.


   Trade sale, an auction by and for the trade, especially
      that of the booksellers.

   Trade wind, a wind in the torrid zone, and often a little
      beyond at, which blows from the same quarter throughout
      the year, except when affected by local causes; -- so
      called because of its usefulness to navigators, and hence
      to trade.
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   Note: The general direction of the trade winds is from N. E.
         to S. W. on the north side of the equator, and from S.
         E. to N. W. on the south side of the equator. They are
         produced by the joint effect of the rotation of the
         earth and the movement of the air from the polar toward
         the equatorial regions, to supply the vacancy caused by
         heating, rarefaction, and consequent ascent of the air
         in the latter regions. The trade winds are principally
         limited to two belts in the tropical regions, one on
         each side of the equator, and separated by a belt which
         is characterized by calms or variable weather.
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WordNet (r) 3.0 (2006):

trade wind
    n 1: steady winds blowing from east to west above and below the
         equator; "they rode the trade winds going west" [syn:
         trade wind, trade]