A slinky is a simple but mesmerizing toy made from a long coil of metal or plastic that can “walk” down stairs by itself. You set it at the top of a staircase, give it a gentle push, and watch as it flips end over end, flowing down each step in a wave-like motion that seems almost alive.

The toy was invented by accident in 1943 when an engineer named Richard James knocked a tension spring off his desk and watched it tumble across the floor. He realized this bouncing, flowing motion would make a perfect toy. The name “Slinky” was chosen because it suggested something sleek and sinuous, which perfectly describes how it moves.

A slinky demonstrates principles of physics like gravity, momentum, and potential energy. When you compress it and let go, it springs back. When you hold it at one end and let it dangle, it creates a beautiful hanging coil. You can even use it to make a “slinky sound” by shaking it or sending waves through the coils.

The word slinky can also be an adjective that describes something that moves in a smooth, flowing way, like a cat with a slinky walk.