According to the online business dictionary, short selling can be defined as follows: "Profiting from an anticipated drop in the price of a commodity, financial instrument, or security by: (1) borrowing and selling it now, or by (2) selling a firm promise (futures contract) to deliver it on a later date at the current (or a specified) price. In either case, the seller counts on buying the item at a cheaper price to return (with a fee) or deliver it. A short seller is a 'bear.' Also called selling short."
Wikipedia defines short selling by stating: It "is the practice of selling a financial instrument that the seller does not own at the time of the sale. Short selling is done with the intent of later purchasing the financial instrument at a lower price. Short-sellers attempt to profit from an expected decline in the price of a financial instrument. Short selling or "going short" is contrasted with the more conventional practice of "going long", which typically occurs when a financial instrument is purchased with the expectation that its price will rise."