Simple words:
* plexus: a network of nerves, blood vessels, or lymphatic vessels
* complex: complicated or intricate
* duplex: having two parts or units
* multiplex: having many parts or units
Less common words:
* simplex: simple or uncomplicated
* complexion: the natural color, texture, and appearance of a person's skin
* duplexity: the state of being double or twofold
* multiplexer: a device that selects one of several input signals and routes it to a single output
* interplex: a connection or link between two or more things
Words with related roots:
* implicate: to show someone to be involved in something
* explicit: stated clearly and in detail
* replicate: to make an exact copy of something
* explicate: to explain in detail
Note: The root "plex" can sometimes be spelled "plec," as in "plectrophone," an old type of musical instrument.