(military, weaponry) direction in which a weapon fires / (figuratively, by extension) position vulnerable to attack

(fine arts) An abstract line supposed to be beautiful in itself and absolutely; differently represented by different authors, often as a kind of elongated S (like the one drawn by Hogarth).

(military) The position of troops drawn up in their usual order without any determined maneuver. / (naval) The line or arrangement formed by vessels of war in an engagement.

(palmistry) A line on the palm of the hand, curving about the base of the thumb, supposed to indicate, by its form or position, the length of a person's life.

(shipbuilding) the outline of a horizontal section of a vessel, as when floating in the water.

(geometry) A line joining centers of figures. / (engineering) A line joining two centers, or fulcra, as of wheels or levers. / A line which determines a dead center.

(engineering) to put in alignment; to put in correct adjustment for smooth running / (transitive) To put things in a line / (intransitive) To get into a line.

(idiomatic) To overstep a boundary, rule, or limit; to go too far or do something unacceptable. / To finish a race. / To achieve completion of something. / To cross the equator, as a vessel at sea.

A spiral marine shell (Fasciolaria distans), of Florida and the West Indies, marked by narrow, dark, revolving lines.

(physics) An imaginary line in a field of force, whose tangent at any point gives the direction of the field at that point and whose number through unit area perpendicular to the field represents its intensity.