Answer:
line of scrimmage
Step-by-step explanation:
In gridiron football, a line of scrimmage is an imaginary transverse line that runs from sideline to sideline (across the width of the football field). It is where you place or put the ball at the end of each play.
If the offense or defense cross the line of scrimmage (LOS) before the ball is snapped or hiked it is offside.