du·​plex | \ ˈdü-ˌpleks How to pronounce duplex (audio) 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


duplexed; duplexing; duplexes

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
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

Staff have identified five aging structures in varying states of disrepair on the property: three single-family homes, one residential duplex and a storage shed. Julie Gallant, Ramona Sentinel, "Mt. Woodson parking lot construction may start next summer," 10 July 2019 The neighborhood is lined with single-family homes and duplexes. Alex Riggins, San Diego Union-Tribune, "At least one person shot in Paradise Hills; SDPD investigating," 5 July 2019 The site shares its eastern property line with duplexes and other low-density housing. Priscella Vega, latimes.com, "Developer appeals Huntington Beach commission's denial of 48-unit residential-commercial project," 3 July 2019 The Legislature was making progress on legislation encouraging development of denser housing units, including duplexes and triplexes. Washington Post, "Oregon GOP walkout threatens paid leave, money for housing," 27 June 2019 Those properties — mostly single family homes and duplexes — are in some of the city’s most troubled neighborhoods. Tony Cook, Indianapolis Star, "Renters lived 'horrible.' Their landlord lived large. The government helped him do it.," 26 June 2019 The products themselves, all reviewed on Amazon, carry the trademark qualities of the e-commerce giant: algorithmic, splashed in primary colors, designed to blend quietly into the corners of duplexes and condos all over the world. Luke Winkie, Vox, "Who are these people who write thousands of Amazon product reviews?," 14 June 2019 Plans have been filed for the first 119 townhouses and duplexes in the future Packing District project, the residential, business and park development from Dr. Phillips Charities. Kyle Arnold, orlandosentinel.com, "Townhouses, duplexes planned for Orlando’s Packing District," 7 June 2019 Cities with at least 10,000 residents would be required to allow duplexes in single-family zones. oregonlive.com, "Plan to eliminate single-family zoning in Oregon neighborhoods headed for key votes," 18 June 2019

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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Statistics for duplex

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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 How to pronounce duplex (audio) , ˈdyü-\

Kids Definition of duplex

: a house with two separate living spaces


du·​plex | \ ˈd(y)ü-ˌpleks How to pronounce duplex (audio) \

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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More from Merriam-Webster on duplex

Rhyming Dictionary: Words that rhyme with duplex

Thesaurus: All synonyms and antonyms for duplex

Spanish Central: Translation of duplex

Nglish: Translation of duplex for Spanish Speakers

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