plexus (n.)

1680s, in anatomy, "an interlacing of nerves, vessels, or fibers," Modern Latin, literally "braid, network," noun use of past participle of Latin plectere "to twine, braid, fold," from suffixed form of PIE root *plek- "to plait." Original use in solar plexus "network of nerves in the abdomen" (see solar). General sense of "net-like arrangement of parts" is from 1760s. Related: Plexal.