Simulate means to create a copy or model of something real, so you can practice, test, or study it safely, without the real risks or costs — pilots train in machines that simulate flying a plane, and scientists simulate weather patterns on computers to predict storms. Simulate can also mean to fake or pretend to have a feeling or condition, to make it look real when it isn't — 'he simulated surprise, though he already knew the news'. Both uses share the same core idea: making something artificial look and act like the real thing.