A part of a bigger system that has its own specific job to do.
The car's cooling subsystem helps keep the engine from overheating.
汽车的冷却子系统有助于防止引擎过热。
A set of parts working together inside a larger system to do something important.
The immune subsystem fights off germs to keep us healthy.
免疫系统帮助我们抵抗细菌,保持健康。