The word "soccer" is actually British. It derives from the game's proper name, association football, with the "soc" bit taken from the word "association" . The reason it came into popular usage was simple: in the 19th century, football and rugby were both commonly known as football, the former dubbed "association football" and the latter "rugby football". But both phrases are a bit of a mouthful, however, so they were popularly shortened to "soccer" and "rugger" to keep things simple.