The term "soccer" originated in England and is derived from the word "association" in "association football," which was used to distinguish it from other forms of football such as rugby football. The word "soccer" was coined in the late 19th century by adding the suffix "-er" to the word "assoc," a common practice in British slang at the time.
When the sport was introduced to America, the name "soccer" was adopted to avoid confusion with American football, which is a completely different sport. Over time, while the rest of the world came to call the sport "football," the term "soccer" remained in common usage in the United States. This distinction helps to clearly differentiate between the two popular sports in America.