To simulate means to imitate or recreate something as closely as possible, usually to learn from it, practice with it, or test how it works. When pilots train in flight simulators, they're not actually flying, but the simulator recreates the experience so realistically that their bodies and brains respond as if they were in a real cockpit. The controls move, the screens show realistic views, and the whole cabin might tilt and shake just like a real plane would.

Scientists use computer programs to simulate everything from weather patterns to how a new bridge will hold up in an earthquake. A simulation lets them see what might happen without building an actual bridge or waiting for a real storm. Video games simulate driving race cars, flying spaceships, or running cities. The better the simulation, the more it feels like the real thing.

The word comes from Latin simulare, meaning “to copy” or “to represent.” When you simulate surprise at a birthday party you knew about all along, you're imitating the reaction you would have had if you were truly surprised. A simulation (noun) is the imitation itself: a flight simulation, a computer simulation, or even a fire drill that simulates an emergency so everyone knows what to do if a real one happens.