an imaginary line parallel to the goal lines that passes from one sideline to the other through the point of the football closest to the goal line of each team.
Origin
1905-10
Examples from the web for line of scrimmage
Some quarterbacks move teams beyond the line of scrimmage.
Branch lined up in the slot between another wide receiver and the line of scrimmage.
Can move defenders out of the way when pulling, showing much better pop on the move than at the line of scrimmage.
Luckily, two pair play on opposite sites of the line of scrimmage, making life for coaches a bit easier.
British Dictionary definitions for line of scrimmage
line of scrimmage
noun
1.
(American football) an imaginary line, parallel to the goal lines, on which the ball is placed at the start of a down and on either side of which the offense and defense line up