Ganglion

n. dense mass of nerve cells (Anatomy)

In anatomy, a ganglion (pl. ganglia) is a tissue mass, which is composed mainly of somata and dendritic structures, which often interconnect with each other to form a complex system of ganglia known as a plexus. These structures provide relay points and intermediary connections between different neurological structures in the body, such as the peripheral and central nervous systems.
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A ganglion is a small, usually hard bump above a tendon or in the capsule that encloses a joint. [more]Ganglion - Community and Resources

Noun
1. an encapsulated neural structure consisting of a collection of cell bodies or neurons
(hypernym) neural structure
(hyponym) autonomic ganglion
(part-holonym) nervous system, systema nervosum

n. ganglion, dense mass of nerve cells (Anatomy)