Sentence:  For the time the Etonians had their way, and it was not until 1867 that the Association adopted its present <WSD>off-side rule</WSD>, which provides that no man can be ' off-side ' unless there are less than three players of the opposite side in front of him when the ball is passed. 
Meaning of the word marked with <WSD> tags:  The prohibition of teammates closer to the opponents' goal than the person kicking or throwing the ball unless there are three opponents at least as close to their goal line.