Ganglion \Gan"gli*on\, n.; pl. L. Ganglia, E. Ganglions. [L. ganglion a sort of swelling or excrescence, a tumor under the skin, Gr. ?: cf. F. ganglion.]

1. (Anat.)
   (a) A mass or knot of nervous matter, including nerve cells, usually forming an enlargement in the course of a nerve.
   (b) A node, or gland in the lymphatic system; as, a lymphatic ganglion.

2. (Med.) A globular, hard, indolent tumor, situated somewhere on a tendon, and commonly formed by the effusion of a viscid fluid into it; -- called also weeping sinew.

Ganglion cell, a nerve cell. See Illust. under Bipolar.

Source: Webster's Revised Unabridged Dictionary (1913)