1.a person or business that buys and sells goods "a car dealer" a person who buys and sells shares, securities, or other financial assets as a principal (rather than as a broker or agent). informal a person who buys and sells drugs. "he posed as a dealer willing to buy heroin" synonyms: trader, merchant, salesman, saleswoman, seller, vendor, purveyor, peddler, hawker; More buyer, merchandiser, distributor, supplier, shopkeeper, retailer, wholesaler "an antique dealer".