Mathematics A path through 2 or more points that shows no curvature, continues on infinitely and can also be broken down to a simple linear equation.
A sentence of dialogue in a script or screenplay, or delivered by an actor or performer. (It's a small part, I have 12 lines in the movie. - Geneveve Bujold in Earthquake.)
The official, stated position of an individual or political faction. (Remember, your answers must match the party line.)
A telephone or network connection. (I tried to make a call, but the line is dead.)
A queue of people, cars, etc. (The line forms on the right.)
A single horizontal row of text on a CRT screen, printed paper, etc.