In the early 1800s in England, football and rugby existed as different variations of the same game. Aristocratic boys came up with the shortened terms “rugger” and “soccer” to differentiate between Rugby Football (from Rugby School, in Warwickshire, England) and Association Football.
According to a letter to The New York Times, published in 1905: “It was a fad at Oxford and Cambridge to use “er” at the end of many words, such as foot-er, sport-er, and as Association did not take an “er” easily, it was, and is, sometimes spoken of as Soccer.”
But by the 1980s, Brits started to turn against the word. “The penetration of the game into American culture,” Stefan Szymanski, a professor of sports economics at the University of Michigan writes, “has led to backlash against the use of the word in Britain."
That doesn't stop the arguments, though. “It’s football not soccer,” one person tweeted, on the night of England’s successful victory over Sweden which propelled the team to the semi-finals. “The English created the game = football.”