Modern gridirons are covered in football players when they're in use, but the original gridirons were more likely to be covered with meat or fish; they were metal gratings used for broiling food over an open fire. In Middle English, such a grating was called a gredil, a root that gave modern English both gridiron and griddle. How did gridiron become associated with football? That happened in the late 1800s, when a white grid pattern was added to football fields to help enforce new rules about how many yards a team had to gain to keep possession of the ball. From high up in the stands, the lines made the playing fields look like cooking gridirons.