ganglion

< /ˈgæŋ gli ə/, gan·gli·ons.

1. Anatomy.
   1. a mass of nerve tissue existing outside the central nervous system.
   2. any of certain masses of gray matter in the brain, as the basal ganglia.
2. Pathology. a cyst or enlargement in connection with the sheath of a tendon, usually at the wrist.
3. a center of intellectual or industrial force, activity, etc.

noun plural -glia (-ɡlɪə) or -glions

1. an encapsulated collection of nerve-cell bodies, usually located outside the brain and spinal cord
2. any concentration of energy, activity, or strength
3. a cystic tumour on a tendon sheath or joint capsule

n.

1680s, from Greek ganglion “tumor,” used by Galen for “nerve bundle.” Of unknown origin; according to Galen, the proper sense of the word was “anything gathered into a ball.”

n. pl. gan•gli•ons

1. A group of nerve cells forming a nerve center, especially one located outside the brain or spinal cord.neuroganglion
2. A benign tumorlike cyst containing mucopolysaccharide-rich fluid enclosed within fibrous tissue and usually attached to a tendon sheath in the hand, wrist, or foot.myxoid cyst synovial cyst

Plural ganglia

1. A compact group of neurons enclosed by connective tissue and having a specific function. In invertebrate animals, pairs of ganglia occur at intervals along the axis of the body, with the forwardmost pair functioning like a brain. In vertebrates, ganglia are usually located outside the brain or spinal cord, where they regulate the functioning of the body’s organs and glands as part of the autonomic nervous system.