In a July speech, President Barack Obama referred to the "middle class" 14 times, defining it as a family making under $250,000 a year. Mitt Romney has looked at it from the other direction, saying that someone who falls into poverty "is still middle class."

In the loose speech of this political season, "middle class" has ballooned to cover just about everyone.

What does the term really mean?

The short answer: There's no official definition. If anything, economic data show a middle class that is shrinking. Mid-wage jobs are disappearing due to automation and outsourcing. The chief White House economist has said the middle class fell from 50 percent of households in 1970 to 42 percent in 2010.

Few academics would say it covers more than 60 percent of households.