Word Smith: Gridiron
Merriam Webster has three definitions for the noun: gridiron
1: a grate for broiling food. “Put the steaks on the gridiron.”
2: something consisting of or covered with a network. “The city was a gridiron of streets.”
3: a football field. “The two teams will face each other on the gridiron.” 
What is the link between these different uses of the word? You have to go way back in the 14th century, when the word “Gridiron” was commonly used to describe a metal grid for cooking over a fire. As Merriam Webster suggests, think of a steak on the grill and the lines created by the hot metal grid.
In the early 20th century, the sport of American football was trying to become easily distinguished from older and more established sports, such as rugby and soccer. Football was a foundling in the US with no significant play outside of the States.
Besides the shape of the ball. the scoring system and the use of body pads, one of the most defining characteristics of American football was the playing field. Until the early 1900’s, football fields were marked in a checkerboard (or grid) pattern, resembling a gridiron.
However, it was not until 1911, when sports writer Claude Miller wrote about football, that the term describing the field stuck. 
“The lines on a football field make a checkerboard effect and have given to the field the name of ‘gridiron.’”
In time, the grid system was ditched for the yard lines and hash marks that we still use today, but the term “gridiron” stuck and sportswriters frequently use the play on the gridiron to distinguish the sport of football from the “pitch” or the “diamond” or the ballfield in general.
 Claude H. Miller used the term gridiron in 1911 for an article he wrote for an issue of Outdoor Sports and Games.