From The Collaborative International Dictionary of English v.0.48 [gcide]:
Dealer \Deal"er\, n.
1. One who deals; one who has to do, or has concern, with
others; esp., a trader, a trafficker, a shopkeeper, a
broker, or a merchant; as, a dealer in dry goods; a dealer
in stocks; a retail dealer.
[1913 Webster]
2. One who distributes cards to the players.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
dealer
n 1: someone who purchases and maintains an inventory of goods
to be sold [syn: trader, bargainer, dealer, monger]
2: a firm engaged in trading
3: a seller of illicit goods; "a dealer in stolen goods"
4: the major party to a financial transaction at a stock
exchange; buys and sells for his own account [syn:
principal, dealer]
5: the person who distributes the playing cards in a card game