1 a [noncount] : the activity or process of buying, selling, or exchanging goods or services : COMMERCE
the trade between the two countries
The tariff is a barrier to trade. = The tariff is a trade barrier.
b : the amount of things or services that are bought and sold : the money made by buying and selling things or services
Trade accounts for half of our gross national product.
The store does a brisk/lucrative trade in T-shirts. [=the store sells a lot of T-shirts]
2 [count] a : the act of exchanging one thing for another
My cupcake for your brownie is a fair/good trade. [=swap]
b US, sports : the act of giving one of your players to another team and getting one of their players in return
The Tigers made a few good trades this season and picked up some promising players.
3 : a job; especially : a job that requires special training and skills and that is done by using your hands
Are you interested in learning a new trade? [=learning the skills that are needed to perform a different job]
She entered the trade [=she began working in her profession] just after graduating from high school.
I am a carpenter/electrician/beautician by trade. [=I work as a carpenter/electrician/beautician]