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

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

Adjective a duplex apartment with all of the bedrooms on the second floor Noun We live in the brick duplex.
Recent Examples on the Web: Noun Anchorage residents Christina and Bob Kelly got into the vacation rental business last summer, after buying and remodeling a South Addition duplex in April 2019. Aubrey Wieber, Anchorage Daily News, "Anchorage Airbnb hosts cut prices and emphasize cleaning in effort to survive pandemic," 3 May 2020 Sanders would rent out a duplex in Riverwest on the short-term rental website Airbnb. Sarah Hauer, Milwaukee Journal Sentinel, "One Twitter user made hilarious guesses about where the presidential candidates would stay during the DNC in Milwaukee," 6 Mar. 2020 His mom rented a duplex in the Hilltop, Columbus’s worst drug district. Paige Williams, The New Yorker, "The Wrong Way to Fight the Opioid Crisis," 3 Feb. 2020 On a residential street populated with brick duplexes in the northeast section of Baltimore, police responded to a shooting and found an injured man in a Mercedes, WMAR reported. Eliott C. Mclaughlin, CNN, "Baltimore leaders demand action after 15 people are shot in 40 hours, five of them fatally," 13 Jan. 2020 Four town-house duplexes, or eight units in all, would be erected on the rear portion of the property, providing a buffer to the adjacent neighborhood. John Laidler, BostonGlobe.com, "Natick selectmen agree to support development of former St. Patrick’s school site," 4 Mar. 2020 The two-alarm blaze appears to have destroyed the duplex, which is at Sixth Avenue and Sherman Street. oregonlive, "2-alarm fire destroys SW Portland duplex," 3 Feb. 2020 Meanwhile, Connaughton's firm is deconstructing a vacant duplex, at 1245-1247 N. Milwaukee St., in order to develop a four-story building with three luxury apartments. Tom Daykin, Milwaukee Journal Sentinel, "Pat Connaughton's investors group to pay $105,000 for city-owned development site on Brady Street," 30 Jan. 2020 Several reticles are available, ranging from standard duplex (the $235 version listed on Amazon) to the uber-useful Wind-Plex. Field & Stream, "10 Best Budget Riflescopes," 12 Sep. 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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Time Traveler for duplex

Time Traveler

The first known use of duplex was in 1567

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Statistics for duplex

Cite this Entry

“Duplex.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/duplex. Accessed 2 Jun. 2020.

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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

Thesaurus: All synonyms and antonyms for duplex

Rhyming Dictionary: Words that rhyme with duplex

Spanish Central: Translation of duplex

Nglish: Translation of duplex for Spanish Speakers

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