As the game became more sophisticated, backs positioned at different depths (i.e. distances behind the forwards) were further differentiated into half back, three quarters (the fraction 3/4) back, and full back, according to English and Scottish nomenclature, or quarter back, half back, and full back in the Irish nomenclature. In rugby the English-Scottish nomenclature was eventually adopted worldwide, with the word, "back", often omitted for brevity from the half back ("half") and three quarters back ("three quarter") names, and "fullback" as a single word.