Linesman

[Ernesto]

A small, insignificant excuse for a football [referee] who runs up and down the line making Hitler style salutes whenever a player is deemed to be in [breach] of the mystical [offside] rule.

[Hina Muqadas]

(in games played on a field or court) an official who assists the referee or umpire from the sideline, especially in deciding on whether the ball is out of play.

[Julian]

Linesman in Tennis. An official who observes a line and decides whether a ball has landed in play or not.

[Julian]

an official in some sports who is responsible for deciding when the ball has crossed the line that marks the edge of the playing area