Grand slam (baseball)

in baseball, a four-base hit with the bases loaded; it always results in four runs scored and four runs batted in, the maximum possible from one hit (or play)

In baseball, a grand slam is a home run hit with runners on first, second, and third base ("bases loaded"). This scores four runs and is the most possible in one play.

According to The Dickson Baseball Dictionary, the term came from the card game of contract bridge. A grand slam in contract bridge involves taking all the possible tricks. The word slam, by itself, can mean a loud sound, such as a door being closed with a lot of force. Slamming the door on one's opponent(s), is similar to the bat slamming the ball into a home run.