octuplex

from The Century Dictionary.

• Eightfold; specifically, of or pertaining to a device or system for sending eight simultaneous telegraphic messages over a single wire.
• noun In telegraphy, an eightfold system; a system permitting of the simultaneous transmission of eight messages over one wire.
• In telegraphy, to adjust or arrange (a telegraphic system) for the simultaneous sending of eight messages.