noun pl. plexuses -·uses or plexus -·us

1. a complexly interconnected arrangement of parts; network
2. Anat. a network of blood vessels, lymphatic vessels, nerves, etc. the solar plexus (of nerves) in the abdomen

Etymology: ModL < L, a twining, braid < pp. of plectere, to twine, braid; akin to plicare: see ply