Definition of duplex in English:

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Pronunciation: /ˈdjuːplɛks/


1North American A residential building divided into two apartments.
Example sentences
  • The property has full planning permission for 30 residential units comprising six three-bedroom townhouses, 12 two-bedroom duplexes and 12 one-bedroom apartments.
  • It notes that three-bed semi-detached houses are on the wane in Dublin, being replaced by smaller two-bed duplexes, townhouses and apartments.
  • Apartments and duplexes became the norm rather than the exception, much to the delight of rookie buyers and older couples trading down.
1.1A flat on two floors: [as modifier]: a plush Mayfair duplex flat
More example sentences
  • The facades suggest that the apartment floor and unit arrangements may be double-height spaces, duplexes, or regular floors carefully hidden behind the cool glass facade.
  • Under the plans the Wheatley would be converted to provide two, two bedroom duplexes and a pair of two bedroom flats.
  • Also available are three-bedroom duplexes on the ground and first floors; these have 105 square metres of accommodation and are selling for €228,000.
1.2chiefly North American & Australian A semi-detached house.
Example sentences
  • The resolution, first reported on Feb.14, would place serious restrictions on the ability of students to live in houses and duplexes.
  • Snowdon residents have been duelling it out by petition concerning Addington House, a drug rehab centre recently transplanted from NDG to a semi-detached duplex at Earnscliffe and Dupuis.
  • Cahaba residents rented from the government until 1947, when the houses and duplexes were sold to individuals at prices ranging from $4,400 to $9,000 each.
2 Biochemistry A double-stranded polynucleotide molecule.
Example sentences
  • In this work, the molar concentrations of the oligonucleotide duplexes are related to the double-stranded molecules 15-bp long.
  • Unlike larger polypeptides and proteins, small nucleic acid duplexes and hairpins do not have a dense core to which this effect would apply.
  • The drugs in the latter complexes are covalently connected by a peptide linker, whereas those associated with the oligonucleotide duplexes are chemically independent species.


1Having two parts, in particular.
1.1North American (Of a house) consisting of two flats.
Example sentences
  • The development comprises a mix of three bedroom townhouses, four bedroom semi-detached and detached houses along with two bedroom apartments and three bedroom duplex houses.
  • The first batch of 40 two-bedroom apartments and three-bedroom duplex houses were completed and sold last February.
  • First-time buyers will be interested in the launch of phase two of Bryanstown Manor, a development of apartments and duplex houses near the train station in Drogheda, Co Louth.
1.2North American (Of a flat) on two floors.
Example sentences
  • The plans provide for eight dwelling-houses, six ground floor apartments, six duplex apartments, an office and all ancillary site works.
  • Well, it wasn't quite the top - there's a second floor to the duplex penthouse we couldn't make it to - but the views are magnificent, largely because the building is taller by half than most everything else in the neighborhood.
  • It will comprise a retail unit, five ground floor flats and eight duplex apartments facing Holborn Street and three ground floor retail units, 17 apartments and 19 car parking spaces facing Markievicz Road.
1.3(Of paper or board) having two differently coloured layers or sides.
Example sentences
  • Finding an optimal schedule for general sheet sequences (e.g., with mixed simplex and duplex sheets in the same document) is still exponential.
  • For instance, a mark engine module controller may export exactly two functions, namely printing a simplex or duplex sheet.
  • However, newer machines can deliver documents either face-up or face-down, and thus simplex sheets are sometimes inverted, while duplex sheets sometimes are not inverted after the second image transfer.
1.4(Of a printer or its software) capable of printing on both sides of the paper.
Example sentences
  • Then we started arguing about how the printer managed to do duplex printing.
  • In order to simultaneously output and input a waveform, the sound card (or sound chip integrated on to the motherboard) must be capable of full duplex operation.
  • Do you need a printer with duplex printing capability (the ability to print on both sides of the paper automatically)?
2(Of a communications system, computer circuit, etc.) allowing the transmission of two signals simultaneously in opposite directions.
Example sentences
  • The duplex circuit, developed in Germany, made it possible for messages to travel simultaneously in opposite directions on the same line.
  • This combination of features enables the user to hear and be heard in even the noisiest environments, while its full duplex communication technology ensures a natural flowing conversation.
  • It, on the other hand, can support full duplex communications.



noun rare


Mid 16th century (as an adjective): from Latin duplex, duplic-, from duo 'two' + plicare 'to fold'. The noun dates from the 1920s.

For editors and proofreaders

Line breaks: du¦plex

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