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

Daphne Campbell registered to vote at this duplex in December of 2013 and kept her voter registration at the address until June 20. Sarah Blaskey And David Smiley, miamiherald, "Where does she live? A Miami lawmaker's bizarre attempt to reside in her district," 3 July 2018 My boyfriend plans to buy a duplex in the next year or so and have her live in the other apartment. Houston Chronicle, "Girlfriend sees trouble ahead with man’s plans for mother," 21 June 2018 The first of the apartment complexes, purchased in 2013, was the Meadows, a subdivision of duplexes in a treeless expanse in a suburb of Atlanta. Aaron C. Davis And Shawn Boburg, chicagotribune.com, "Sean Hannity's properties in low-income areas take an aggressive approach to rent collection," 11 May 2018 Meanwhile, five miles west of NoMa in a tidy duplex in the Deanwood neighborhood, the slain youth’s parents sat in the heavy stillness of their living room, speaking in low tones on a summerlike Friday as sunlight poured through a window. Paul Duggan, Washington Post, "‘Tyshon’s dying!’ A frantic call sent a D.C. mother to her son, stabbed in a melee, but it was too late.," 6 May 2018 During that period, Campbell campaigned and won a seat in the state Senate and voted using the address of the Metellus' duplex. Sarah Blaskey And David Smiley, miamiherald, "Where does she live? A Miami lawmaker's bizarre attempt to reside in her district," 3 July 2018 Lauren Barber, who lived in the next-door unit of the duplex and called 911 after hearing screams, told The Bee that her fiancé Josh Estrella was one of the neighbors to hold down Lynch until the police arrived. Angel Guerrero, sacbee, "Man convicted of attempted murder in 2017 Citrus Heights stabbing," 15 June 2018 The vigil was held in the front yard of the duplex where Girard lived with her 14-year-old daughter, who escaped the shooting. Max Londberg, kansascity, "Neighbors, relatives memorialize victims of triple murder-suicide at Northland vigil," 12 June 2018 Perhaps the flashiest part of the duplex is the kitchen, which showcases snazzy lacquered red cabinets. Kelsey Kloss, ELLE Decor, "He even mentions 560 State Street in his award-winning "Empire State Of Mind."," 14 Nov. 2016

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).


the setting in which something occurs

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