Recession can be defined as the decline in the Gross Domestic Product (GDP) of a country for two of more consecutive quarters of a financial year. We can also say that the negative growth of an economy that last more than a few months can be termed as a recession. Negative growth can be seen in employment, investment spending, capacity utilization, household income.
To read more about recession, follow this link : http://en.wikipedia.org/wiki/Recession