du·​plex | \ˈdü-ˌpleks also ˈdyü- \

Definition of duplex 

(Entry 1 of 3)

1a : having two principal elements or parts : double, twofold

b : having two complementary polynucleotide strands of DNA or of DNA and RNA

2 : allowing telecommunication in opposite directions simultaneously



Definition of duplex (Entry 2 of 3)

transitive verb

: to make duplex



Definition of duplex (Entry 3 of 3)

: something duplex: such as

a : a 2-family house

b : duplex apartment

c : a duplex molecule of DNA or of RNA and DNA

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Synonyms & Antonyms for duplex

Synonyms: Adjective

binary, bipartite, double, double-barreled, double-edged, dual, twin, twofold

Antonyms: Adjective


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Did You Know?

Duplex can describe a confusing variety of things, depending on the technical field. Most of us use it as a noun: a duplex can be either a two-family house or a two-story apartment. In computer science and telecommunications, duplex (or full-duplex) communication can go in both directions at once, while half-duplex communication can go only one way at a time. In other areas, just translate duplex as "double" and see if the sentence makes sense.

Examples of duplex in a Sentence


a duplex apartment with all of the bedrooms on the second floor


We live in the brick duplex.

Recent Examples on the Web: Noun

The breakdown is 30 individual multiplex (apartment) units, 25 cottages and 15 duplexes. Bill Banks, ajc, "Plan for old UMCH property favors passive, ‘park-like’ green space," 30 June 2018 The largest suite the Empire Suite, which is a three-bedroom duplex designed by Thierry Despont, with views of Central Park from the floor-to-ceiling windows. Brooke Bobb, Vogue, "Where Rihanna, Gigi Hadid, and More Celebrities Get Ready for the Met Gala," 7 May 2018 Boehr, 77, told me her personal residence wasn't significantly damaged, but one of the rental properties, a pair of duplexes, is now covered with nearly two feet of mud and debris. David Lazarus, latimes.com, "It's unclear if homeowners' insurance covers mudslide damage," 30 Jan. 2018 Doyle said the tornado struck between 7:05 and 7:08 p.m. Jenny Kummer was at home in her duplex on Trask Street when her husband's cell phone notified them of a tornado warning. Susan Demar Lafferty, Daily Southtown, "Tornado damage closes Manhattan post office," 27 June 2018 He was arrested after neighbors smelled a strong odor of gasoline near their Lake Mist Drive duplex. Chelsea Prince, ajc, "Kennesaw man gets life in prison for killing wife of 20 years, dousing her body with gasoline," 7 June 2018 Carson recently purchased a pre-construction duplex that Courtney simultaneously designed. Danielle Fox, ELLE Decor, "A Feminine—And Feminist—Apartment in Hell’s Kitchen Goes Big," 21 May 2018 Musician Tré Cool, best known as the drummer for punk rock outfit Green Day, has an offer in hand but is still accepting backup bids for his Newport Beach duplex, according to the MLS. Jack Flemming, latimes.com, "Green Day drummer Tré Cool snares a buyer in Newport Beach," 16 May 2018 Jost said a private funder has purchased a duplex near Ridgeview Road and Sheridan Street in Olathe. Lynn Horsley, kansascity, "Where's the growing homeless population in Kansas' wealthiest county? Not in shelters | The Kansas City Star," 27 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'duplex.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of duplex


1567, in the meaning defined at sense 1a


1833, in the meaning defined above


1922, in the meaning defined above

History and Etymology for duplex


Latin, from duo two + -plex -fold — more at two, -fold

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Time Traveler for duplex

The first known use of duplex was in 1567

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More Definitions for duplex



English Language Learners Definition of duplex

: a building that is divided into two separate homes

: an apartment with two floors


du·​plex | \ˈdü-ˌpleks, ˈdyü-\

Kids Definition of duplex

: a house with two separate living spaces


du·​plex | \ˈd(y)ü-ˌpleks \

Medical Definition of duplex 

: a molecule having two complementary polynucleotide strands of DNA or of DNA and RNA

Other Words from duplex

duplex adjective

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Comments on duplex

What made you want to look up duplex? Please tell us where you read or heard it (including the quote, if possible).


obstinately defiant of authority

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