A cord is a length of flexible material, thicker than thread but thinner than rope, used to tie, connect, or secure things. You might use a cord to bundle newspapers for recycling, hang a pendant around your neck, or connect your headphones to a device. Electrical cords carry power from outlets to lamps, computers, and other equipment.

A cord sits right in the middle of that family: thread is the thinnest, then comes string, then cord, then rope, then thick cable. When you see a bungee cord or a power cord, you're looking at something flexible enough to bend and coil, but strong enough to do serious work.

In a completely different meaning, a cord is also a unit for measuring stacked firewood: specifically, a pile that's 4 feet high, 4 feet deep, and 8 feet long. Loggers and firewood sellers still use this measurement today.

You might also encounter cord in anatomy: your spinal cord carries signals between your brain and body, and your vocal cords vibrate to produce sound when you speak or sing. These aren't actual cords you could tie in knots, but they got their names because early anatomists thought they looked like thin ropes or strings inside the body.