ganglion

gan·gli·on   (gāng'glē-ən)    n.   pl. gan·gli·a (-glē-ə) or gan·gli·ons Anatomy A group of nerve cells forming a nerve center, especially one located outside the brain or spinal cord. A center of power, activity, or energy. Pathology A benign cystic lesion resembling a tumor, occurring in a tendon sheath or joint capsule. [From Greek, cystlike tumor, nerve bundle.] gan'gli·on'ic (-ŏn'ĭk) adj.

ganglion 

Main Entry: gan·gli·on
Pronunciation: 'ga[ng]-glE-&n
Function: noun
Inflected Form: plural gan·glia /-glE-&/ also gan·gli·ons
1 : a small cystic tumor (as on the back of the wrist) containing viscid fluid and connected either with a joint membrane or tendonsheath
2 : a mass of nerve tissue containing nerve cells: a : an aggregation of such cells forming an enlargement upon a nerve or upon two or more nerves at theirpoint of junction or separation b : a mass of gray matter within the brain or spinal cord : NUCLEUS 2—see BASAL GANGLION

ganglion gan·gli·on (gāng'glē-ən)
n. pl. gan·gli·ons or gan·gli·a (-glē-ə)

1. A group of nerve cells forming a nerve center, especially one located outside the brain or spinal cord. Also called 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. Also called myxoid cyst, synovial cyst.

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gan'gli·al adj.