Definitions of trade:

• noun:   the skilled practice of a practical occupation

  Example: "He learned his trade as an apprentice"

• noun:   the commercial exchange (buying and selling on domestic or international markets) of goods and services

  Example: "Venice was an important center of trade with the East"

• noun:   the business given to a commercial establishment by its customers
• noun:   a particular instance of buying or selling

  Example: "I had no further trade with him"

• noun:   people who perform a particular kind of skilled work

  Example: "As they say in the trade"

• noun:   steady winds blowing from east to west above and below the equator

  Example: "They rode the trade winds going west"

• noun:   an equal exchange
• verb:   exchange or give (something) in exchange for
• verb:   turn in as payment or part payment for a purchase

  Example: "Trade in an old car for a new one"

• verb:   engage in the trade of
• verb:   be traded at a certain price or under certain conditions

  Example: "The stock traded around $20 a share"

• verb:   do business; offer for sale as for one's livelihood