And I hate to break this to you, but that is actually a commonly held misbelief about the technical definition of recession. See here: http://en.wikipedia.org/wiki/Recession
Well, technically anytime output decreases it is a recession. However, you need at least 2 quarters to assure that it is sustained. That is, we worry about it if it's more than one quarter.
And the point is that no matter if it's one quarter or two, if you want to talk about just output or output and income, etc., it is measurable. It is not debatable. It's a yes or no question.
And the former economics professor in my weeps that Wikipedia was your first source for a definition.
From the San Fran Fed
A significant decline in general economic activity extending over a period of time.
From the Economist magazine.
Broadly speaking, a period of slow or negative economic GROWTH, usually accompanied by rising UNEMPLOYMENT. Economists have two more precise definitions of a recession. The first, which can be hard to prove, is when an economy is growing at less than its long-term trend rate of growth and has spare CAPACITY. The second is two consecutive quarters of falling GDP.
Finally, from McConnell and Brue's Economics (16th ed., McGraw-Hill)
...a period of decline in total ouput, income, employment, and trade. This downturn, which lasts 6 months or more, is marked by...