From Longman Dictionary of Contemporary Englishlinesmanlines‧man /ˈlaɪnzmən/ noun (plural linesmen /-mən/) [countable] DSan official in a sport who decides when a ball has gone out of the playing area
Examples from the Corpus
linesman• Benedettini clawed the ball out with his right hand, but a linesman raised his flag to indicate a goal.• Both linesmen and the referee had poor games with bad off-sides decisions being given against both sides.• If this was not disgraceful behaviour, they also threw coins and plastic etc. at the linesman, referee and Linfield players!• Robins coolly beat Hallworth then turned to watch a flock of blue shirts besiege the linesman to no avail.• The referee awarded a penalty and, after consulting the linesman, ordered an early bath for Sansome.• When I went to the linesman he told me to clear off.• The linesman said it was for a push and handball. 