The vagus nerve.
[Latin vagus, wandering, uncertain.]
The vagus nerve is heavily branched and connects the brain with the heart, lungs, and stomach and to other upper digestive organs. The most common term is vagotomy, a surgical operation in which one or more branches of the vagus nerve are cut, typically to reduce gastric secretion in treating peptic ulcers; a person or animal subjected to this has been vagotomized. Something vagolytic acts to disrupt or impede the action of the vagus nerve.