duplex

American  

[doo-pleks, dyoo-] / ˈdu plɛks, ˈdju- /

noun

• duplexes
  plural

1. duplex apartment.

2. duplex house.

3. paper or cardboard having different colors, finishes, or stocks on opposite sides.

4. Printing.

   1. a method of reproducing an illustration using two halftone plates, one black and the other in a color.

   2. a printing press equipped to print both sides of a sheet in one pass.

5. Genetics. a double-stranded region of DNA.

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adjective

1. having two parts; double; twofold.

2. (of a machine) having two identical working units, operating together or independently, in a single framework or assembly.

3. pertaining to or noting a telecommunications system, as most telephone systems, permitting the simultaneous transmission of two messages in opposite directions over one channel.

verb (used with object)

1. to make duplex; make or change into a duplex.

   Many owners are duplexing their old houses for extra income.

duplex British  

/ ˈdjuːplɛks /

noun

1. a duplex apartment or house

2. a double-stranded region in a nucleic acid molecule

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adjective

1. having two parts

2. machinery having pairs of components of independent but identical function

3. permitting the transmission of simultaneous signals in both directions in a radio, telecommunications, or computer channel

Other Word Forms

Derived Forms

• duplexity
  noun

Inflected Forms

Nouns

• duplexes
  plural

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Etymology

Origin of duplex

1810–20; < Latin: twofold, double, equivalent to du ( o ) two + -plex -plex

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Explanation

A two-family house can be called a duplex. Living in a duplex is great — unless the people with whom you share a wall like to have all-night yodeling parties. In the U.K. a duplex is an apartment with an upstairs and a downstairs, but in North America a duplex is a building divided into two separate living spaces. Most duplexes are built with the two homes side by side, although you can also live in a duplex with apartments on two floors. The Latin duplex means "twofold," from duo, "two," and -plex, "to intertwine." The word was coined in the U.S. around 1922.

Example Sentences

See Examples For:

duplex duplexes

“We now live in a large duplex with our landlady and her daughter,” Maggie tells me.

From Slate ● Oct. 28, 2026

In June, real-estate investor Justin Smith closed on a duplex in Roscoe, Ill. — about 90 miles west of Chicago — for $250,000.

From MarketWatch ● Oct. 17, 2026

“I lived in a duplex with my grandparents and saw them downstairs every morning,” Elsesser says.

From Los Angeles Times ● Sep. 7, 2026

Before that, about 10 years ago, he rented a room in a duplex for $333; that same room now rents for $900, he says.

From BBC ● Jul. 18, 2026

When my mother returned home, she found our duplex padlocked.

From "Three Little Words: A Memoir" by Ashley Rhodes-Courter

Housing reforms that increase supply, such as allowing smaller lots in new subdivisions, permitting duplexes, townhomes, and backyard cottages on existing lots, and changing zoning laws to allow housing nearer to jobs, are land-use issues.

From Barron's ● Jun. 24, 2026

The measure defines a big institutional investor as an entity that controls 350 homes or more, and its definition of a single-family home includes duplexes along with traditional detached houses.

From MarketWatch ● Jun. 22, 2026

About 250 other structures — duplexes, apartment buildings, condominium complexes — were also destroyed or damaged, those officials said.

From Los Angeles Times ● Jan. 7, 2026

Fueling the anxiety: a raft of recent California laws and bills that make it easier to build duplexes and apartment buildings in single-family neighborhoods like Altadena.

From The Wall Street Journal ● Oct. 13, 2025

She wanted to show us the other side of Marguerite Cartwright Avenue, where the seasoned professors lived, with the duplexes hemmed in by gravely driveways.

From "Purple Hibiscus" by Chimamanda Ngozi Adichie

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