The term 'Gridiron Upright' is a combination of two crossword solutions: Gridiron and Upright. Gridiron is a term used to describe the playing field for American football, which is marked with a series of parallel lines that form a grid-like pattern. Upright is a term used to describe the goalposts at either end of the field, which are tall vertical structures used to mark the end zones. Together, Gridiron Upright refers to the goalposts on an American football field.