Four years ago, the president of the World Bank got up before a well-heeled Princeton audience and declared the Third World over.

“If 1989 saw the end of the Second World with Communism’s demise, then 2009 saw the end of what was known as the Third World,” Robert Zoellick announced. Economies were newly rising, power shifting: “North and South, East and West, are now points on a compass, not economic destinies,” he said.

On its face, it was an odd proposition. For starters, Zoellick was about two decades late: Were the meaning of the Third World true to its origins, it should have died when the Cold War did. Then again, the meaning of the Third World has been slippery almost since its conception. Though Zoellick and many others consider the term passé, it lingers — in journals, in books, on the lips of subalterns throughout the world. Maybe that’s because no alternative has as pliable a meaning.

More on that in a moment. But first, some Third World datapoint:

Date of Birth: August 14, 1952

Place of Birth: L’Observateur, a French weekly

Proud Papa: Alfred Sauvy, French demographer and the first director of the Institut National des Etudes Démographique.

Circumstances of Birth: Sauvy wrote a column, “Trois Mondes, Une Planète,” that worried that poor countries would get lost in the Cold War. Engaged in an arms race, the capitalist West and communist East would neglect world hunger, poverty, and disease. And it would be to their peril, he warned. “After all, this Third World — ignored, exploited, scorned like the Third Estate — wants to be something, too.”

Sauvy’s French audience would know that Third Estate allusion.  ...