1. （足球、网球等运动中的）边线裁判员，巡边员，司线员
A linesman is an official who assists the referee or umpire in games such as football and tennis by indicating when the ball goes over the lines around the edge of the field or court.

1. a person who installs or repairs electrical or telephone lines

Synonym: electricianlineman

2. official (in tennis, soccer, football, etc.) who assists the referee in some way (especially by watching for out of bounds or offside)