A "Grand Slam" is a term used in sports, particularly in tennis and golf, to describe a significant achievement. In tennis, it refers to winning all four major tournaments in a single calendar year: the Australian Open, French Open, Wimbledon, and the US Open. This feat is incredibly challenging and showcases a player's exceptional skill and consistency. In golf, a Grand Slam means winning all four major championships in one year: the Masters Tournament, the U.S. Open, the Open Championship, and the PGA Championship. Achieving a Grand Slam in either sport is a rare and celebrated accomplishment, marking a player as one of the best in their field.