Ganglion (thing)

1. Any mass or knot found within the body.
2. A mass or knot of nerve cells which may be located inside or outside of the brain or spinal cord.
3. A type of benign (noncancerous) cystlike tumor which can arise in the tendons of the wrist or base of the foot. It is long and fibrous with clear liquid at the center.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.