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

Officials have red-tagged two properties, including a duplex with three units.

From Los Angeles Times ● Oct. 9, 2026

A mortgage on a house you can comfortably afford or buying that duplex I mentioned above to earn some rental income are perfectly fine examples of “good” debt.

From MarketWatch ● Oct. 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

This side faces a big duplex apartment house.

From "Things Not Seen" by Andrew Clements

She vowed to bring “gentle density” — duplexes, triplexes and fourplexes — to single-family neighborhoods that are near public transit hubs.

From Los Angeles Times ● Nov. 5, 2026

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

They mostly invested in real estate — two commercial buildings and two residential duplexes.

From MarketWatch ● Nov. 11, 2025

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

It rose deftly from a small neighborhood of duplexes, laundromats, and mom-and-pop restaurants, mostly Korean and soul food.

From "Anger Is a Gift" by Mark Oshiro

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