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.
Here's how lightning works. Lightning is an electric current, and just like the electricity lurking in the outlets in your house, it can be deadly. Have you ever gotten a shock by shuffling across a carpet and then touching something made of metal? Then you've experienced the same process that makes lightning.