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."
ganglion gan·gli·on (gāng'glē-ən)
n. pl. gan·gli·ons or gan·gli·a (-glē-ə)
A group of nerve cells forming a nerve center, especially one located outside the brain or spinal cord. Also called neuroganglion.
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.
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.