ganglion

noun

gan·​gli·​on ˈgaŋ-glē-ən 

plural ganglia ˈgaŋ-glē-ə  also ganglions

1

: a small cystic tumor connected either with a joint membrane or tendon sheath

2

a

: a mass of nerve tissue containing cell bodies of neurons external to the brain or spinal cord

also : nucleus sense 2b

b

: something likened to a nerve ganglion

a ganglion of cables and wires

ganglionated

ˈgaŋ-glē-ə-ˌnā-təd 

adjective

ganglionic

ˌgaŋ-glē-ˈä-nik 

adjective

Examples of ganglion in a Sentence

Recent Examples on the Web

The whale had, at most, 180 retinal ganglion cells per square millimeter; humans, meanwhile, have up to about 40,000 in the same area. —Margherita Bassi, Smithsonian Magazine, 21 May 2025

For instance, in 2015, Texas A&M scientists found that implanting electrodes into a cockroach's ganglion (the neuron cluster that controls its front legs) was remarkably effective at successfully steering the roaches 60 percent of the time. —Jennifer Ouellette, ArsTechnica, 2 May 2025

Researchers say that happens when bright light enters the inner surface of the retina where neurons called retinal ganglion cells are located. —Anuradha Varanasi, Forbes, 4 Nov. 2024

There are treatments that may help, such as smell training or a procedure known as a stellate ganglion block. —Linda Carroll, NBC News, 22 Oct. 2024

Word History

Etymology

borrowed from Latin, borrowed from Greek ganglíon "tumor on a tendon, mass of nerve tissue (thought to resemble such tumors)," of obscure origin

First Known Use

1597, in the meaning defined at sense 1

Phrases Containing ganglion

• basal ganglion
• dorsal root ganglion
• spinal ganglion

Rhymes for ganglion

• aileron
• antiphon
• autobahn
• carillon
• castellan
• celadon
• cephalon
• chitosan
• cynodon
• denouement
• deuteron
• echelon

Kids Definition

ganglion

noun

gan·​gli·​on ˈgaŋ-glē-ən 

plural ganglia -glē-ə  also ganglions

: a mass of nerve tissue lying outside the brain or spinal cord and containing neurons

also : nucleus sense c

ganglionic

ˌgaŋ-glē-ˈän-ik 

adjective

Medical Definition

ganglion

noun

gan·​gli·​on ˈgaŋ-glē-ən 

plural ganglia -glē-ə  also ganglions

1

: a small cystic tumor (as on the back of the wrist) containing viscid fluid and connected either with a joint membrane or tendon sheath

2

a

: a mass of nerve tissue containing cell bodies of neurons that is located outside the central nervous system and forms an enlargement upon a nerve or upon two or more nerves at their point of junction or separation

b

: a mass of gray matter within the brain or spinal cord : nucleus sense 2 see basal ganglion