Bear Market
In stock markets, the price of stock is generally a reflection of future prospects of cash flow and profit for companies. But when prospects begin to wane(=become less) and expectations fall, prices of stock can start to decline.
Usually, this term is used to describe when an overall market or index falls, but it can also be used to describe when individual securities prices fall at least 20% for a sustained period of time - typically for two months or more.
When a bear market tends to occur, the amount of stocks that are sold tends to increase. Investors will often turn to short-selling or put options to try and make money during a bear market as prices fall. Likewise, those with stocks invested in companies will often look to sell their stock, to avoid losing significant value from their initial investments.
See also
Cash Flow Statement
Financial Markets