Every time the World Cup rolls around, the rest of the world likes to remind Americans that the sport is called football, not soccer. And while the United States' usage ofsoccer may seem as strange as its reliance on the imperial system instead of metric units, some of the hate might be unwarranted. A recent University of Michigan study traced the popularity of both terms for the sport and found that despite the prevalence of the word soccer in England between the 1960s and the 1980s, a lot of people consider it a uniquely American term and respond to it with "anger and frustration."