Also from Wikipedia: While national definitions vary, two consecutive quarters of decline in a country's real gross domestic product is commonly used as a practical definition of a recession.

From the Oxford dictionary (recession): a period of temporary economic decline during which trade and industrial activity are reduced, generally identified by a fall in GDP in two successive quarters.

It's only now that we're seeing all this slimy lawyering about the definition of recession. "Well acksually, technically..."