n [ usu sing ]
the achievement of winning three important victories in certain sports. It originally meant winning three important horse races: the Derby (II), the St Leger and the Two Thousand Guineas . It is also used in Rugby Union , where it refers to one of the four countries, England, Ireland, Scotland and Wales, defeating the other three in the same season. In the US, the phrase refers to victories in the country’s three most important horse races: the Preakness Stakes, the Belmont Stakes and the Kentucky Derby :
win/take the triple crown.