plexus (n.) Look up plexus at Dictionary.com
1680s, 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." Used of a network, such as solar plexus "network of nerves in the abdomen" (see solar). Related: Plexal.