A device is a tool or piece of equipment made for a specific purpose. Your phone is a device for communication, a thermometer is a device for measuring temperature, and a can opener is a device for opening cans. The word suggests something cleverly designed to solve a particular problem or accomplish a certain task.

Devices can be simple or complex. A lever that helps you pry open a stuck window is a device. So is a computer. What makes something a device is that someone created it intentionally to do something useful. A rock isn't a device, but a stone hammer shaped by human hands is.

The word also appears in a clever phrase: when someone leaves you to your own devices, they're letting you figure things out by yourself, trusting you to use your own methods and ideas.

In stories, you might encounter a plot device, which is a technique writers use to move their story forward. For example, when a character conveniently finds a map to the hidden treasure, that map is a plot device.