Define the term simulation
From Computer Science Wiki
A simulation is the creation of a model that can be manipulated logically to decide how the physical world works
A simulation is an imitation of the operation of a real-world process or system. The act of simulating something first requires that a model be developed; this model represents the key characteristics, behaviors and functions of the selected physical or abstract system or process. The model represents the system itself, whereas the simulation represents the operation of the system over time. 
- Define the term simulation
Give the precise meaning of a word, phrase, concept or physical quantity.