\Quad"ru*plex\, a. [L., from quattuor four + plicare to fold.] Fourfold; folded or doubled twice. {Quadruplex system} (Electric Telegraph), a system by which four messages, two in each direction, may be sent simultaneously over the wire.
A kind of telegraphy system developed by Thomas A. Edison in the 1870s combining diplex and duplex communications to support simultaneous transmission of two messages in each direction.
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