trade 
(trād)
(trād)n.
1. The business of buying and selling commodities, products, or services; commerce. See Synonyms at business.
2. A branch or kind of business: the women's clothing trade.
3. The people working in or associated with a business or industry: writers, editors, and other members of the publishing trade.
4. The activity or volume of buying or selling: The trade in stocks was brisk all morning.
5. An exchange of one thing for another: baseball teams making a trade of players.
6. An occupation, especially one requiring skilled labor; craft: the building trades.
7. trades The trade winds.
v. trad·ed, trad·ing, trades
v.intr.
1. To engage in buying and selling for profit.
2. To make an exchange of one thing for another.
3. To be offered for sale or be sold: Stocks traded at lower prices this morning.
4. To shop or buy regularly: trades at the local supermarket.
v.tr.
1. To give in exchange for something else: trade farm products for manufactured goods; will trade my ticket for yours.
2. To buy and sell (stocks, for example).
3. To pass back and forth: We traded jokes.
adj.
Phrasal Verbs: 1. Of or relating to trade or commerce.
2. Relating to, used by, or serving a particular trade: a trade magazine.
3. Of or relating to books that are primarily published to be sold commercially, as in bookstores.
trade down
To trade something in for something else of lower value or price: bought a new, smaller car, trading the old one down for economy.
trade in
To surrender or sell (an old or used item), using the proceeds as partial payment on a new purchase.
trade on
To put to calculated and often unscrupulous advantage; exploit: children of celebrities who trade on their family names.
trade up
To trade something in for something else of greater value or price: The value of our house soared, enabling us to trade up to a larger place.
[Middle English, course, from Middle Low German.]
trada·ble, tradea·ble adj.