Moment

The measure of rotation about a reference object when a force is applied.

Reference Point

With respect to a point, the product of the intensity of the force into the perpendicular distance from the point to the line of direction of the force.

Reference Line

With respect to a line, the product of that component of the force which is perpendicular to the plane passing through the line and the point of application of the force, into the shortest distance between the line and this point.

Reference Plane

With respect to a plane that is parallel to the force, the product of the force into the perpendicular distance of its point of application from the plane.