Say it like this

A thing built to do a job that would otherwise take a person a lot of effort.

For the grown-up

A machine converts energy into useful work. A lever is a machine. So is a dishwasher and so is a data centre. The word is broader than children expect and usefully so.

The easy mistake

Careful here. Every machine was designed by somebody for a purpose. When a machine produces an unwelcome result, the design is where to look.

Words next to this one

Robot A machine with a body that does a job, and somebody had to teach it how. Computer A machine that follows instructions very fast and never gets bored of doing the same thing again. Invent To make something that did not exist before, usually because you got annoyed about a problem.