(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.

A straight line along which an observer has a clear view. / (weaponry) The line which passes through the front and rear sight, at any elevation, when they are sighted at an object.

(mathematics) A logarithmic line on a Gunter's scale, which is used to perform the multiplication and division of numbers mechanically with only dividers.

(geomorphology) A geomorphologic unconformity marking a boundary between an upland region and a plane; sometimes marked by a series of waterfalls on rivers that cross it.

(physics) any of a series of dark lines in the solar spectrum; due to the absorption of light by atoms and molecules in the Sun's atmosphere

(chiefly Forteana) A supposed alignment of ancient sacred sites, such as megalith structures, along straight lines of mystical power.