dealer (n.)youdaoicibaDictYouDict[dealer 词源字典]
Old English dælere "divider, distributor; agent, negotiator," agent noun from deal (v.). Meaning "player who passes out the cards in a game" is from c. 1600; meaning "one who deals in merchandise" is from 1610s. Illegal drug sense is recorded by 1920.[dealer etymology, dealer origin, 英语词源]