Gridiron pastime is a phrase commonly used to refer to American football. However, there are many synonyms that can be used in place of this phrase. For example, one can use "pigskin sport" which refers to the leather ball used in the game. "Touchdown game" is another option because the primary objective of American football is to score touchdowns. "Field sport" is also appropriate because the game is played on a field. Other synonyms include "tackle sport," "fall sport," and "contact sport." With these words, you'll be able to talk about American football without ever having to use the phrase "gridiron pastime" again.