While calling the world's most popular sport "soccer" is typically depicted as a symbol of American ignorance, the reason we don't call it "football" like the rest of the world is Britain's fault.
The word "soccer" is a British invention that British people stopped using only around 40 years ago, according to a 2014 paper by University of Michigan professor Stefan Szymanski.
The word "soccer" comes from the use of the term "association football" in Britain, and goes back 200 years.
In the early 1800s, a bunch of British universities took "football" — a medieval game — and started playing their own versions of it, all under different rules. To standardize things across the country, these games were categorized under different organizations with different names.
One variant of the game you played with your hands became "rugby football." Another variant came to be known as "association football" after the Football Association formed to promote the game in 1863, 15 years after the rules were made at Cambridge.
"Rugby football" became "rugger" for short, then "rugby". "Association football" became "soccer."
After these two sports spread across the Atlantic, Americans invented their own variant of the game that they simply called "football" in the early 1900s.
"Association football" became "soccer" in America, and what was called "gridiron" in Britain became simply "football" in America.
Most British people stopped saying 'soccer' because it's what Americans called it
The interesting thing here is that Brits still used "soccer" regularly for a huge chunk of the 20th century. Between 1960 and 1980, "soccer" and "football" were "almost interchangeable" in Britain, Szymanski found.
Then everything changed (via Szymanski):
"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 high point of the NASL around 1980."
Most British people stopped saying "soccer" because of its American connotations, however, UK broadcaster Sky Sports still used it to brand wildly-popular TV shows "Soccer Saturday" and "Soccer A.M."
So, no, it's not wrong to call it "soccer" if you're American.
