OB

OB is a gaming and sports acronym that stands for out-of-bounds. It is the area outside of the specified field of play.

Whether it be in sports or games there is a marked field of play that the player must remain in or else he or she will be penalized. In video games, the player may die or lose health whereas in sports you usually lose possession of the ball or stop the clock. In golf, you will most likely lose a stroke if you hit it out-of-bounds.