A rod is a long, straight, thin piece of rigid material, like wood, metal, or plastic. A fishing rod helps you cast your line far out into the water. A curtain rod holds up your bedroom curtains. A lightning rod on top of a building attracts lightning strikes safely away from the structure.

You might also hear about rods and cones, which are tiny rod-shaped cells in your eyes that help you see. The rods detect light and dark, especially in dim conditions, which is why they're named after their shape.

In older measurements, a rod was also a unit of length equal to 16.5 feet. Surveyors once used actual measuring rods of this length to map out property lines and fields. You might still see “rods” mentioned in old property deeds or historical descriptions of land, though today we use feet and meters.