nervous system
Americannoun
-
nervous systems
plural
-
the system of nerves and nerve centers in an animal or human, including the brain, spinal cord, nerves, and ganglia.
-
a particular part of this system.
noun
-
The system of neurons and tissues that regulates the actions and responses of vertebrates and many invertebrates. The nervous system of vertebrates is a complex information-processing system that consists mainly of the brain, spinal cord, and peripheral and autonomic nerves. It receives chemical information from hormones in the circulating blood and can also regulate secretions of the endocrine system by the action of neurohormones. The nervous systems of invertebrates vary from a simple network of nerves to a complex nerve network under the control of a primitive brain.
-
See also autonomic nervous system central nervous system peripheral nervous system
Other Word Forms
Noun Inflected Forms
Etymology
Origin of nervous system
First recorded in 1730–40
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
These projections carry signals from nerve cells to other cells, allowing information to travel across the nervous system.
From Science Daily ● Oct. 23, 2026
MS is an autoimmune disease that affects the central nervous system and can result in progressive physical and cognitive decline.
From Los Angeles Times ● Oct. 20, 2026
These cells normally protect the nervous system by removing debris, responding to injuries, and helping maintain a healthy environment for neurons.
From Science Daily ● Oct. 19, 2026
Lead poisoning is "particularly harmful to young children" and can "severely damage the brain and central nervous system", according to the World Health Organization.
From BBC ● Oct. 17, 2026
My nervous system launched into “Flight of the Bumblebee.”
From "Middlesex: A Novel" by Jeffrey Eugenides
![]()
Random Word
Spin the wheel and learn a new word!
Get a wordDefinitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.