The parasympathetic nervous system is responsible for a variety of bodily functions such as digestion, relaxation, and sleep. However, there are synonyms that can be used to describe this system as well. One synonym is the "rest and digest" system, as it promotes relaxation and slows down the body's functions. Another term that can be used is the "craniosacral division," as the parasympathetic nervous system has two main components located in the head and lower back. Lastly, the "vegetative nervous system" can also be used as a synonym, as the parasympathetic system controls the automatic functions of the body, such as breathing and heart rate.