Definition of grand slams:
(n) :
(sports) The winning of all available, major or specified events in a given year or sports season.
(n) :
(baseball) The hitting of a home run with the bases loaded.
(n) :
(bridge) The bid and winning of all the tricks during the play of one hand.
(n) :
(motor racing) The situation in which a racer starts from pole position, then wins first place while leading during the entire race, while also recording the fastest lap of the race.
(n) :
(roller derby) The situation in which the jammer laps the opposing team's jammer, scoring five points.
(n) :
(tennis) The four biggest competitions of the year: Wimbledon, the French Open, Australian Open and the US Open