1 In this sense it is nearly synonymous with synopsis. ( 2 n.) The tracing of things to their source, and the resolving of knowledge into its original principles. ( 3 n.) A syllabus, or table of the principal heads of a discourse, disposed in their natural order.
A lightning rod or lightning conductor is a iron rod that is used to make lightning strike it, rather than strike something else. It is part of a lightning protection system. Such a system is made of many such rods. These rods are usually placed at high points of buildings and structures.
The lightning rod was first used in England in 1760 on the Eddystone Lighthouse, a wooden structure that had been previously destroyed by lightning. Despite the success of Franklin's device, some viewed it as a hazard, claiming that the pointed rods favored by Franklin actually attracted lightning strokes to a building.