As the FIFA World Cup kicks off in Brazil this week, fans of the globe's most popular sport have been tuning in to watch the greatest names in the game square off. But one question continues to crop up: Why is it that Americans insist on calling the sport "soccer," while the rest of the world calls it "football"?

A recent paper by University of Michigan professor Stefan Szymanski says the Brits are partly to blame.

The word "soccer," which is believed to have originated in Britain some 200 years ago, comes from the official name of the sport, "association football." As other versions of the game evolved to include Rugby Football, it is believed the Brits adopted colloquialisms to distinguish each game.

"The rugby football game was shortened to 'rugger,' a term recognized in British English to the present day, and the association football game was, plausibly, shortened to 'soccer'" Szymanski writes. (Apparently ending words in "er" was a fad back then.)

Gradually, the term "soccer" gained popularity in the U.S. to distinguish the sport from American football. By the 1980s, the Brits began to part with the term, apparently, because it had become too "American."

"In the U.S. it seems to have had a more democratic flavor – everyone used it – and more easily shifted from a colloquialism to a proper name because of the utility of distinguishing it from the other 'football'," Szymanski explains in his paper, which was published in May. "Since 1980 the usage of the word 'soccer' has declined in British publications, and where it is used, it usually refers to an American context. This decline seems to be a reaction against the increased usage in the US which seems to be associated with the highpoint of the [North American Soccer League] around 1980."

Americans' use of the term "soccer" continues to incite frustration among those loyal to the original name of the game. Don't believe us? Just take Daniel Gooch's rant on Bleacher Report for example:

"I can't count the number of times i have been speaking to an American and felt the urge bang their head against the wall so it gets into there head that they are wrong ... If you are an American it is time to put your burger down and change your ways. Ok, you can call 'your' sport football, but when it comes to 'our' football, don't call it soccer!"

Need another example? Szymanski points to this lecture from Beat Zimmermann, the founder of the Air Navigation Institute:

“Dear Americans, Here is an important lesson for you to learn: There is no sport called 'Soccer.' The sport that was invented between the years 220 and 680 (yes, years with 3 digits do exist) is called Football. Nobody knows why you guys call a sport that was invented somewhat later (1869) and is played by motorbikers (that's why they wear helmets, not so?) football. It's neither played with the feet nor with a ball. If you called it American Rugby I am sure nobody would argue.”

Well, there you have it, folks.