http://www.investopedia.com/terms/t/tradingdesk.asp
Definition of 'Trading Desk'
A desk where transactions for buying and selling securities occur. Trading desks can be found in most organizations (banks, finance companies, etc.) involved in trading investment instruments such as equities, fixed-income securities, futures, commodities and
foreign exchange. A trading desk provides traders with access to instantaneous trade executions. Also known as "dealing desk".
Investopedia explains 'Trading Desk'
Trading desks can be either large or small depending on the organization and are occupied by licensed traders, usually specializing in trading one particular type of investment product (e.g. forex traders, commodities traders, stock traders, etc.). The instantaneous
trade executions can be particularly important for day traders looking for arbitrage opportunities that usually last only minutes or even seconds.
Definition of 'Dealing Desk'
In foreign currency markets, the location of a financial institution's forex dealers. Since the forex market is open around-the-clock, many institutions have dealing desks around the world. Dealing desks can also be found outside the foreign exchange markets,
such as in banks and finance companies, to execute trades in securities.
Investopedia explains 'Dealing Desk'
The term "desk" may be a bit of a misnomer, given its connotation of a table shared by a couple of traders. Large financial institutions often have dealing facilities that are staffed by hundreds of dealers. In a large institution, major currencies, such as
the euro and yen, may have several dealing desks staffed by dozens of traders who specialize in these currencies.