lines·man 
(līnzmən)
(līnzmən)n.
1. Football An official who marks the downs and the position of the ball and watches for certain violations from the sidelines.
2. Sports
a. An official in various court games whose chief duty is to call shots that fall out of bounds.
b. An official in soccer and other field games who indicates when the ball has gone out of bounds.
c. Either of two officials in ice hockey who call icing and offsides, conduct face-offs, and call penalities.
3. See lineman.