This term is used in football to classify a play in which action is reversed laterally before advancing forward. In a typical of this type, the quarterback hand the ball off to a player who then runs a short distance to one side and then hands the ball off to another player who is moving in the opposite direction who continues with the ball in that direction. The goal of the play is to catch the other team off guard as they all moved to the side the ball was originally travelling. If the play is executed successfully, the offense should be able to pin the defense to one side of the field while the rusher gains yardage.
This play is sometimes known as a trick-play because it attempts to outright fool the defense. There are many ways for the defense to combat a reverse. Beyond keeping an eye on the ball and not being fooled, defenders who suspect a reverse may position themselves closer to the reverse route. On some teams, the defense is disciplined and sticks to their assignments and does not over commit to one side (meaning the entire defense does rush to one side of the field). By keeping balance on the field, the defense is able to pursue the reverse well and tackle the player before any significant gain is made.