Meaning

noun the act of imitating the behavior of some situation or some process by means of something suitably analogous (especially for the purpose of study or personnel training)

noun (computer science) the technique of representing the real world by a computer program

noun representation of something (sometimes on a smaller scale)

originFirst attested in 1340 as Middle English symulacioun, from Middle French simulation, from Old French simulation/simulacion, from Latin simulātiōnem, from simulō (“imitate”). Morphologically simulate + -ion.

Etymology from Wiktionary, CC BY-SA 3.0