traffic has 1 distinct synonym spread across 1 of its 6 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 aggregation of things (pedestrians or vehicles) coming and going in a particular locality during a specified period of time
buying and selling; especially illicit trade
the amount of activity over a communication system during a given period of time
“heavy traffic overloaded the trunk lines”
social or verbal interchange (usually followed by `with')
trade or deal a commodity
“They trafficked with us for gold”
Synonyms, antonyms and the broader and narrower relations for traffic come from Princeton University’s WordNet. Full sources and licences.