Borrowed from Latin duplex (“double, two-fold”), from duo (“two”) + plico (“fold together”); compare the roots of διπλόος (diplóos, “double”); compare also πλέκω (plékō, “twist, braid”). By surface analysis, duo- +‎ -plex.

• (General American) enPR: do͞o'plĕks, IPA^(key): /ˈdu.plɛks/

• Audio (Southern England):

  (file)

• Rhymes: -uːplɛks

duplex (not comparable)

1. Double; made up of two parts.
   1. (architecture) Having two floors.
   2. (architecture) Having two units, divisions, suites, or apartments.
   3. (metallurgy) Of stainless steel: having a structure containing austenite and ferrite in roughly equal proportions.
      • 2010, Harold M. Cobb, The History of Stainless Steel, Materials Park, O.H.: ASM International, →ISBN, page 189:

        Duplex stainless steels have been classified according to the first period (1930–1960) and second period (1960–1990). The designations for these duplex alloys in the United States have been primarily according to Unified Numbering System (UNS) numbers in the S3xxx.x series.

2. (telecommunications) Bidirectional (in two directions).

   Antonyms: simplex, unidirectional

   duplex telegraphy

3. (soil science) Having horizons with contrasting textures.
   • 1977, Australian Journal of Botany, volume 25, page 462:

     Soils are duplex, sandy and solodic. The dominant trees are the stringybark eucalypts […]

(bidirectional):

• full duplex
• half-duplex
• semiduplex

duplex (plural duplexes or duplices)

1. (US, Canada, Australia) A house made up of two dwelling units.

   Synonym: (British) semi-detached house

   • 2020, Akwaeke Emezi, The Death of Vivek Oji, Faber & Faber Ltd, page 53:

     The house had been renovated into a duplex and he’d put in a phone line.

2. (US) A dwelling unit with two floors.
3. (philately) A cancellation combining a numerical cancellation with a second mark showing time, date, and place of posting.
4. (juggling) A throwing motion where two balls are thrown with one hand at the same time.
5. (biochemistry) A double-stranded polynucleotide.
6. (geology) A system of multiple thrust faults bounded above and below by a roof thrust and floor thrust.
   • 1993, David J. Lidke, Jack Burton Epstein, Chester A. Wallace, U.S. Geological Survey Bulletin, page 16:

     In contrast, the folds in the overlying lithotectonic unit 4 are larger and are cut by a series of faults in a duplex.

   • 1995, Robert D. Hatcher, Structural Geology: Principles, Concepts, and Problems, page 211:

     It has been noted, using a combination of surface geologic and seismic reflection data, that a duplex, although formed in response to movement of a thrust sheet, frequently arches the thrust sheet as the duplex is built by duplication of rocks beneath it […]

duplex (third-person singular simple present duplexes, present participle duplexing, simple past and past participle duplexed)

1. To make duplex.
2. To make into a duplex.
3. (juggling) To make a series of duplex throws.

• Duplex on Wikipedia.Wikipedia
• Duplex stainless steel on Wikipedia.Wikipedia

Borrowed from Latin duplex, see above.

• IPA^(key): /dy.plɛks/

• Audio (France (Vosges)):

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• Audio (Canada (Shawinigan)):

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• Audio (France (Somain)):

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duplex m (invariable)

1. a link between two points, such as a cable or a wire
2. duplex, maisonette (dwelling)

• duplexer

• “duplex”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012

Unadapted borrowing from Latin duplex.

duplex m (invariable)

1. (telecommunications) duplex (communications link allowing simultaneous sending and receiving)
2. (telephony) party line
3. (telephony) telephone or telephone user on a party line
4. (metallurgy) duplex process (for refining steel)
5. (architecture) two-story residence with separated living and sleeping areas
6. (typography) duplex matrix (matrix bearing two signs next to each other)

Equivalent to duo (“two”) +‎ -plex (“-fold”). Possibly inherited from Proto-Italic *dupleks, if Umbrian 𐌕𐌖𐌐𐌋𐌀𐌊 (tuplak) is cognate (however, its meaning is uncertain and its form poses some difficulty).^[1] The Italic form may be an analogical alteration (with the du- of duo replacing *dwi-) of an original Proto-Indo-European *dwi-pleḱ-s; compare Ancient Greek δίπλαξ (díplax).

• (Classical Latin) IPA^(key): [ˈdʊ.pɫɛks], [ˈdʊp.ɫɛks]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈduː.pleks], [ˈdup.leks]

duplex (genitive duplicis, adverb dupliciter); third-declension one-termination adjective

1. twofold, two, double
   • 44 BCE, Cicero, De officiis 1.104:

     Duplex omnīnō est iocandī genus, ūnum illīberāle, petulāns, flāgitiōsum, obscēnum, alterum ēlegāns, urbānum, ingeniōsum, facētum.

     In all, there are two kinds of joking: one ignoble, irreverent, shameful, obscene; the other elegant, refined, ingenious, witty.

     (literally, “In all, the kind of joking is twofold: …”)

   • 29 BCE – 19 BCE, Vergilius, Aeneis 4.469–470:

     [...] Eumenidum velutī dēmēns videt agmina Penthēus,
     et sōlem geminum et duplicīs sē ostendere Thēbās [...].

     Just as the deranged Pentheus sees the ranks of Eumenides, and a twin sun, and Thebes to show herself twofold.
     (Variant accusative plural: duplicīs. For context, see: The Bacchae.)

2. bipartite, cloven

   Synonyms: biceps, anceps

3. ambiguous

Third-declension one-termination adjective.

• Sg.Abl. sometimes duplice.

• “duplex”, in Charlton T. Lewis and Charles Short (1879), A Latin Dictionary, Oxford: Clarendon Press
• “duplex”, in Charlton T. Lewis (1891), An Elementary Latin Dictionary, New York: Harper & Brothers
• "duplex", in Charles du Fresne du Cange, Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• “duplex”, in Gaffiot, Félix (1934), Dictionnaire illustré latin-français, Hachette.
• Carl Meißner; Henry William Auden (1894), Latin Phrase-Book‎^[1], London: Macmillan and Co.
  • a twofold tradition prevails on this subject: duplex est memoria de aliqua re
    
  • in two, three columns: agmine duplici, triplici
    

Borrowed from French duplex.

duplex n (plural duplexuri)

1. duplex