The Collaborative International Dictionary of English v.0.48:

Lineman \Line"man\ (l[imac]n"m[a^]n), n.; pl. Linemen
   (l[imac]n"m[e^]n).
   1. One who carries the line in surveying, etc.; the surveyor
      who marks positions with a range pole.
      [1913 Webster]

   2. A man employed to examine the rails of a railroad to see
      if they are in good condition; also, a man employed to
      install or repair telegraph, telephone, television cable,
      or power lines. Also called linesman.
      [1913 Webster]

   3. (Football) A player whose position is in the first
      (forward) line, as opposed to a back; one who plays on
      the line of scrimmage. specifically: a center, guard, or
      tackle.
      [PJC]

   4. A ladies' man who is especially adept at inventing
      effective introductory phrases (pick-up lines) to gain a
      woman's attention. [Colloq.]
      [1913 Webster]

   5. the position of a player on a football team who is
      stationed on the line of scrimmage. [WordNet sense 4]
      [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

linesman \linesman\ n.
   1. the official (in tennis or soccer) who watches the lines.
      [WordNet 1.5]

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

   Syn: electrician, lineman.
        [WordNet 1.5] Line-up

WordNet (r) 3.0 (2006):

linesman
    n 1: official (in tennis, soccer, football, etc.) who assists
         the referee in some way (especially by watching for out of
         bounds or offside)
    2: a person who installs or repairs electrical or telephone
       lines [syn: electrician, lineman, linesman]