These are English terms that mean big hit or grand hit. In the Sport of Tennis is the way to call the 4 biggest tournaments of this sport : Australia, Roland Garros, Wimbledon and U.S. Open. It's a term taken from the bridge game. It's a move that gets 1000 additional points with 13 bases if you're not vulnerable and 1500 if you're vulnerable. The term grand slam is also used in baseball, to indicate a home run with all bases full which means 4 runs.
GRAND SLAM on bridge : greater contract that can be tendered and fulfilled, which requires promising to make all 13 tricks in any of the 5 denominations (7ST, 7? , 7? , 7? , 7? ) . In tennis: these are the 4 major tournaments organized by the WTA, namely the US Open, Roland Garrós, Wimbledon and Australia.
