of or relating to a system in telegraphy by which four messages can be sent on one wire simultaneously. (adjective)
A quadruplex system (noun)
Examples of word quadruplex
The quadruplex was the tempting goal toward which Edison now constantly turned, and after more than a year's strenuous work he filed a number of applications for patents in the late summer of 1874.
Thus by combining instruments that respond only to variation in the strength of current from the distant station, with instruments that respond only to the change in the direction of current from the distant station, and by grouping a pair of these at each end of the line, the quadruplex is the result.
Note 32: The edition I will be using is that of 1624, Bibliotheca mundi Vincentii Burgundi … Speculum quadruplex, naturale, doctrinale, morale, historiale (Douai, Balthazar Bellerus).
Configured as a quadruplex, the apartment includes three bedrooms, four and a half bathrooms, 13-foot ceilings, a media room, library and private terrace.
At East 64th Street, Mr. Mottola's lavish quadruplex sits on one of the most exclusive-and expensive-blocks in Manhattan.