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

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. —Ashley Belanger, ArsTechnica, 22 Aug. 2025

The ventral ganglion is a collection of nerves found on an arrow worm’s belly and is a biological feature unique only to them. —Stephanie Edwards, Discover Magazine, 25 July 2025

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

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