Quintuplex

This was entered 1 ♅. iii., in November, 1776, and had the honour of being the object to which the grand forty-foot reflector was first directed, in February, 1787, under the designation of “quadruple.” As a trapezium it was gazed at, measured, and delineated, for upwards of fifty years, when Σ. announced it “quintuplex,” by the addition of the little star E.

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The use of those scientific duplex, quadruplex, and even quintuplex systems could then safely be brought into general use, and this would render possible much cheaper telegraphy.

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We need to point out that in some critical missions, the performance and reliability of a triplex system may not be high enough. In this case, the level of redundancy needs to be increased beyond a triplex system—a quintuplex system (K = 1, N = 5) or a double-triplex system (K = 2, N = 3).

Source: wiktionary

Indeed, physiologically considered, the liver is the great original duplex, while anatomically, it is the enigmatical quintuplex; for it has five lobes, five vessels, five ligaments, five fissures, and, singularlly^([sic]) enough, five letters spells its name.

Source: wiktionary