/ˌparəˌsimpəˈTHetik/
Noun
1. Primarily modulates visceral organs such as glands. Responses are never activated en masse as in the fight-or-flight sympathetic response. While providing important control of many tissues, the parasympathetic system, unlike the sympathetic system, is not crucial for the maintenance of life. (global.britannica.com)
2. Of or relating to the part of the automatic nervous system that counterbalances the action of the sympathetic nerves. It consists of nerves arising from the brain and the lower end of the spinal cord and supplying the internal organs, blood vessels, and glands. (Google Dictionary)
3. The part of the autonomic nervous system that contains chiefly cholinergic fibers, that tends to induce secretion, to increase the tone and contractility of smooth muscle, and to slow heart rate, and that consists of a cranial and a sacral part. (merriam-webster.com)
4. Originates in the brain stem and lower part of the spinal cord; opposes physiological effects of the sympathetic nervous system: stimulates digestive secretions; slows the heart; constricts the pupils; dilates blood vessels. (wordnetweb.princeton.edu)
Also written as: PSNS, PNS
Word origin: From para- “beside” + from Modern Latin sympatheticus, from Greek sympathetikos, from sympathein, from sympathes “having a fellow feeling, affected by like feelings.”