In economics, the term recession describes the reduction of a country's gross domestic product (GDP) for at least two quarters.^[1][2] The usual dictionary definition is "a period of reduced economic activity", a business cycle contraction.^[3][4]

The United States-based National Bureau of Economic Research (NBER) defines economic recession as: "a significant decline in [the] economic activity spread across the country, lasting more than a few months, normally visible in real GDP growth, real personal income, employment (non-farm payrolls), industrial production, and wholesale-retail sales."^[5] The NBER's Business Cycle Dating Committee is generally seen as the authority for dating US recessions. Almost universally, academic economists, policy makers, and businesses defer to the determination by the NBER for the precise dating of a recession's onset and end.

from: http://en.wikipedia.org/wiki/Recession 3/17/09