Which term describes a complete series of events in an engine cycle?

The term "cycle" is the most appropriate choice to describe a complete series of events in an engine cycle. In the context of engines, a cycle typically refers to the sequence of events that occur during one complete operation of the engine, such as the intake, compression, power, and exhaust strokes in a four-stroke engine. This term effectively encapsulates the repetitive nature of engine operations, as each cycle leads to the ongoing functioning of the engine.

The other terms, while related in some ways, do not specifically capture the essence of a complete series of events in the same way. "Process" implies a series of actions or steps that might not necessarily return to the starting point, while "sequence" highlights the order of events without emphasizing their cyclical nature. "Circuit" usually pertains to a closed path for electrical current rather than a process sequence specific to engine operations. Thus, "cycle" distinctly represents the comprehensive loop of operations that characterize engine performance.