trade has 12 distinct synonyms spread across 10 of its 12 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the commercial exchange (buying and selling on domestic or international markets) of goods and services
“Venice was an important center of trade with the East”
a particular instance of buying or selling
“it was a package deal”
steady winds blowing from east to west above and below the equator
“they rode the trade winds going west”
an equal exchange
“we had no money so we had to live by barter”
turn in as payment or part payment for a purchase
“trade in an old car for a new one”
Synonyms, antonyms and the broader and narrower relations for trade come from Princeton University’s WordNet. Full sources and licences.