Which term refers to one or more equations that depict how a system functions?

The term that refers to one or more equations depicting how a system functions is the mathematical term. In mathematics, equations are used to represent relationships between different variables in a system, allowing for analysis, predictions, and interpretations of the system's behavior.

Mathematical equations can describe a wide range of systems, from physical processes to abstract concepts, and they provide a precise language to model complex behaviors in a structured way. This allows for problem-solving and understanding of how different components of a system interact with one another.

The other options, while related to different fields or concepts, do not encapsulate the idea of using equations to represent system behavior in the way that mathematics does. Statistical refers to data analysis and interpretation rather than a direct representation through equations, literal pertains more to language and meanings rather than mathematical representation, and philosophical deals with reasoning and thought rather than the quantitative specification of systems. Thus, the correct choice is mathematical, as it directly aligns with the use of equations in understanding and depicting system functions.