The term 'ROD' is a three letter word that can be used in a variety of contexts. In fishing, a ROD is a long, flexible pole with a line and hook attached to it, used to catch fish. It is also used in carpentry and other construction projects to measure distances and angles. In physics, a ROD is a unit of length equal to one-twelfth of a foot. In electricity, a ROD is a metal conductor used to carry an electric current. Finally, in astronomy, a ROD is a unit of distance equal to 3.26 light years.