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.
Interpretation 1: The rod is a wooden stick used to hit a child and generate pain: Most conservative Christian sources which discuss the rod in Proverbs imply that it is a wooden stick of some sort which a parent should use to hit a misbehaving child, causing them pain, and thereby discipline them.