The word “soccer” originated in England, and was originally used to differentiate association football from its rugby cousin. Just as rugby football was shortened to “rugger”, the game of association football became known as “soccer” thanks to a shortening of the word “association”.

The word soccer comes from an abbreviation for Association (from Association Football, the ‘official’ name for the game) plus the addition of the suffix –er. This suffix (originally Rugby School slang, and then adopted by Oxford University), was appended to ‘shortened’ nouns, in order to form jocular words.

The word association was used to distinguish their specific sport from other popular games of the day such as “rugby football.” The word soccer comes from a slang abbreviation of the word association, which British players of the day adapted as “assoc,” “assoccer” and eventually soccer or soccer football.

soccer (n.) 1889, socca, later socker (1891), soccer (1895), originally university slang (with jocular formation -er (3)), from a shortened form of Assoc., abbreviation of association in Football Association (as distinguished from Rugby football).

In a paper from 2014, Szymanski writes that “soccer” originated in late 19th century England, as a way of differentiating between variants of the game which at that time did not have a commonly agreed-upon set of rules.