linesman

noun6

1. •
   An assistant referee.

   • A linesman replaced injured referee Rebecca Welch after 50 minutes and with no other official present, qualified referee Pattison, 60, ran the line. — 2015
2. •
   An official whose primary task is to watch the blue line and determine when there has been an offside.
3. •
   An official whose primary task is to determine whether there has been a line of scrimmage violation.
4. •
   (old-fashioned) A male line judge.
5. •
   A person employed to work on electrical lines; a lineman.
6. •
   A private in the line.