# dual
## English
### Alternative forms

* du. (abbreviation, grammar)

### Etymology

* PIE word
* *dwóh₁
Borrowed from Latin dualis (“two”), from duo (“two”) + adjective suffix -alis.

### Pronunciation

* (UK) enPR: dyo͞oʹəl, jo͞oʹəl; IPA: /ˈdjuː.əl/, /ˈdʒuː.əl/
* (US) enPR: d(y)o͞o'əl; IPA: /ˈd(j)u.əl/
* Audio (UK):(file)
* Rhymes: -ʊəl
* Homophones: duel; jewel (yod-coalescence)

### Adjective

dual (not comparable)
* Characterized by having two (usually equivalent) components.
    Synonyms: double, twin; see also Thesaurus:dual
    a dual-motor vehicle
* Pertaining to two, pertaining to a pair of.
    Synonyms: double, duplicate; see also Thesaurus:twofold
    dual engine failure
    dual citizenship
** 2020, Grace Ying May, “Women Disciplining Men: A Biblical Pattern of Leadership”, in Aída Besançon Spencer, William David Spencer, editors, Christian Egalitarian Leadership: Empowering the Whole Church According to the Scriptures, page 48:Both Deborah and Samuel held dual roles as judges and prophets.
* (grammar) Pertaining to a grammatical number in certain languages that refers to two of something, such as a pair of shoes.
    Coordinate terms: singular, trial, plural
    Modern Arabic displays a dual number, as did Homeric Greek.
* (mathematics, physics) Exhibiting duality.
* (linear algebra) Being the space of all linear functionals of (some other space).
** 2012, Doug Fisher, Hans-J. Lenz, Learning from Data: Artificial Intelligence and Statistics V, Springer Science & Business Media, →ISBN, page 81:Accordingly, a hyperplane in the sample space is dual to a subspace in the variable space.
* (category theory) Being the dual of some other category; containing the same objects but with source and target reversed for all morphisms.
    Synonym: opposite
** 1992, Colin McLarty, Elementary Categories, Elementary Toposes, Clarendon Press, →ISBN, page 77:Every category is dual to its own dual, so if a statement holds in all categories so does its dual.

#### Derived terms

* bidual
* codual
* coduality
* dual audio
* dual-band
* dual-boot
* dual boot
* dual-braked
* dual cab
* dual-capable aircraft
* dual citizen
* dual citizenship
* dual-clutch gearbox
* dual-coding theory
* dual control
* dual degree
* dual earner
* dual economy
* dual-edged sword
* dual-exceptional
* dual federalism
* dual-frequency
* dual graph
* dual heritage
* dual house
* dualic
* dualie
* dualisation
* dualism
* dualist
* dualistic
* duality
* dualization
* dualize
* dually
* dual mandate
* dual meet
* dual mode, dual-mode
* dual monastery
* dual nationality
* dual offence
* dual phenomenology
* dual photon absorptiometry
* dual polyhedron
* dual-ported
* dual primary
* dual-purpose
* dual resident
* dual school
* dual-sector model
* dual sensory impaired
* dual SIM
* dual-SIM
* dualski
* dual tone multi-frequency
* dual-tropic
* dual-use
* dual-use research of concern
* dual-voltage
* duloxetine
* Hodge dual
* isodual
* nondual
* non-self-dual
* predual
* pseudodual

#### Translations

    The translations below need to be checked and inserted above into the appropriate translation tables. See instructions at Wiktionary:Entry layout § Translations.

### Noun

dual (plural duals)
* Of an item that is one of a pair, the other item in the pair.
* (geometry) Of a regular polyhedron with V vertices and F faces, the regular polyhedron having F vertices and V faces.
    The octahedron is the dual of the cube.
* (grammar) The dual number.
* (mathematics) Of a vector in an inner product space, the linear functional corresponding to taking the inner product with that vector. The set of all duals is a vector space called the dual space.
* (wrestling) A head-to-head match or meet between two teams, such as two high schools or colleges.
** 2010 August 3, Kevin Revolinski, Insiders' Guide® to Madison, WI, Rowman & Littlefield, →ISBN, page 137:Wrestling duals and meets take place at the Wisconsin Field House. There are no advance single event ticket sales.
** 2014 November 18, Mark Schultz, David Thomas, Foxcatcher: The True Story of My Brother's Murder, John du Pont's Madness, and the Quest for Olympic Gold, Penguin, →ISBN:But Dave agreed to participate in the Bulgarian dual, and that trapped me into having to wrestle, too.
** 2023 October 19, Jason Norman, American Women in Amateur Wrestling, 2000-2022, McFarland, →ISBN, page 203:Early in 2021, she became the first female to compete and win a match at the Ter-Hark Cup wrestling dual, helping her squad to victory.

#### Derived terms

* categorical dual
* first-person dual
* second-person dual
* self-dual
* third-person dual

#### See also

* (grammatical numbers) grammatical number; singular, dual, trial, quadral, quintal, paucal, plural
* unal
* duel

### Verb

dual (third-person singular simple present duals, present participle (UK) dualling or (US) dualing, simple past and past participle (UK) dualled or (US) dualed)
* (transitive) To convert from single to dual; specifically, to convert a single-carriageway road to a dual carriageway.
** 1994, Great Britain. Parliament. House of Commons, Parliamentary Debates:I have to declare an interest and I do so with some ambivalence because if the road is dualled it is likely to take half of my front garden.
** 2006, David Lowe, Intermodal Freight Transport, page 163:The power generation and propulsion systems are dualled to accommodate component failure and maintain propulsion at reduced speed should any part of one system be lost.
** 2021 September 22, “Network News: Nexus increases Tyne and Wear Metro train order to 46”, in RAIL, number 940, page 23:The investment will allow Nexus to increase service frequencies, reduce journey times, and improve reliability by dualling three sections of line between Pelaw and South Shields.

### Anagrams

* Auld, Daul, Dula, auld, laud, udal

## French
### Pronunciation

* Audio:(file)

### Adjective

dual (feminine duale, masculine plural duaux, feminine plural duales)
* dual

### Noun

dual m (plural duaux)
* dual

### Further reading

* “dual”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012.

## German
### Pronunciation

* IPA: [duˈaːl]
* Hyphenation: du‧al
* Audio:(file)
* Rhymes: -aːl

### Adjective

dual (strong nominative masculine singular dualer, not comparable)
* dual

#### Declension
### Further reading

* “dual” in Duden online
* “dual” in Digitales Wörterbuch der deutschen Sprache

## Irish
### Pronunciation

* IPA: /d̪ˠuəl̪ˠ/, /d̪ˠuəlˠ/

### Etymology 1

From Old Irish dúal (“tress, lock of hair”), from Proto-Celtic *doklos, from Proto-Indo-European *doḱlos (compare Icelandic tagl (“horse’s tail”), Old English tæġl, English tail).

#### Noun

dual m (genitive singular duail, nominative plural duail)
* lock, tress
    Synonyms: dlaoi, dual gruaige
* wisp, tuft
    Synonym: dlaoi
* ply, strand
* twist, twine
* spiral, whirl

##### Declension

bare forms
singular
plural
nominative
dual
duail
vocative
a dhuail
a dhuala
genitive
duail
dual
dative
dual
duail
forms with the definite article
singular
plural
nominative
an dual
na duail
genitive
an duail
na ndual
dative
leis an dual don dual
leis na duail :

##### Derived terms

* dualach$^1$
* duailín, dualán

#### Verb

dual (present analytic dualann, future analytic dualfaidh, verbal noun dualadh, past participle dualta)
* (transitive) twine
* (transitive) braid, coil
* (transitive) interlace, fold

##### Conjugation

| verbal noun | dualadh | dualadh | dualadh | dualadh | dualadh | dualadh | dualadh | dualadh |
| past participle | dualta | dualta | dualta | dualta | dualta | dualta | dualta | dualta |
| tense | singular | singular | singular | plural | plural | plural | relative | autonomous |
| tense | first | second | third | first | second | third | relative | autonomous |
| indicative |||||||||
| present | dualaim | dualann tú; dualair$^†$ | dualann sé, sí | dualaimid | dualann sibh | dualann siad; dualaid$^†$ | a dhualann; a dhualas / a ndualann* | dualtar |
| past | dhual mé; dhualas | dhual tú; dhualais | dhual sé, sí | dhualamar; dhual muid | dhual sibh; dhualabhair | dhual siad; dhualadar | a dhual / ar dhual* | dualadh |
| past habitual | dhualainn / ndualainn‡‡ | dhualtá / ndualtá‡‡ | dhualadh sé, sí / ndualadh sé, sí‡‡ | dhualaimis; dhualadh muid / ndualaimis‡‡; ndualadh muid‡‡ | dhualadh sibh / ndualadh sibh‡‡ | dhualaidís; dhualadh siad / ndualaidís‡‡; ndualadh siad‡‡ | a dhualadh / a ndualadh* | dhualtaí / ndualtaí‡‡ |
| future | dualfaidh mé; dualfad | dualfaidh tú; dualfair$^†$ | dualfaidh sé, sí | dualfaimid; dualfaidh muid | dualfaidh sibh | dualfaidh siad; dualfaid$^†$ | a dhualfaidh; a dhualfas / a ndualfaidh* | dualfar |
| conditional | dhualfainn / ndualfainn‡‡ | dhualfá / ndualfá‡‡ | dhualfadh sé, sí / ndualfadh sé, sí‡‡ | dhualfaimis; dhualfadh muid / ndualfaimis‡‡; ndualfadh muid‡‡ | dhualfadh sibh / ndualfadh sibh‡‡ | dhualfaidís; dhualfadh siad / ndualfaidís‡‡; ndualfadh siad‡‡ | a dhualfadh / a ndualfadh* | dhualfaí / ndualfaí‡‡ |
| subjunctive |||||||||
| present | go nduala mé; go ndualad$^†$ | go nduala tú; go ndualair$^†$ | go nduala sé, sí | go ndualaimid; go nduala muid | go nduala sibh | go nduala siad; go ndualaid$^†$ | — | go ndualtar |
| past | dá ndualainn | dá ndualtá | dá ndualadh sé, sí | dá ndualaimis; dá ndualadh muid | dá ndualadh sibh | dá ndualaidís; dá ndualadh siad | — | dá ndualtaí |
| imperative |||||||||
| – | dualaim | dual | dualadh sé, sí | dualaimis | dualaigí; dualaidh$^†$ | dualaidís | — | dualtar |
* indirect relative † archaic or dialect form ‡‡ dependent form used with particles that trigger eclipsis

### Etymology 2

(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.)

#### Noun

dual m (genitive singular duail, nominative plural duail)
* dowel
* knot (in timber)
    Synonyms: alt, cranra

##### Declension

bare forms
singular
plural
nominative
dual
duail
vocative
a dhuail
a dhuala
genitive
duail
dual
dative
dual
duail
forms with the definite article
singular
plural
nominative
an dual
na duail
genitive
an duail
na ndual
dative
leis an dual don dual
leis na duail :

##### Derived terms

* dualach$^2$
* dualbhata

### Etymology 3

From Old Irish dúal (“that which belongs or is proper to an individual by nature or descent”), from Proto-Indo-European *dʰewgʰ-.

#### Adjective

dual (genitive singular masculine duail, genitive singular feminine duaile, plural duala, comparative duaile)
* native, natural
    Is dual dó a bheith leisciúil. ― He is naturally lazy.
    Ní dual don diabhal bheith díomhaoin.No rest for the wicked.(literally, “It is not in the devil's nature to be idle.”)
* proper, fitting
* in the natural order of things
* fated
* possible

##### Declension

$^1$ When the preceding noun is lenited and governed by the definite article. $^2$ When the preceding noun ends in a slender consonant.

##### Related terms

* dualgas

### Mutation

Note: Certain mutated forms of some words can never occur in standard Modern Irish. All possible mutated forms are displayed for convenience.

### Further reading

* Ó Dónaill, Niall (1977) “dual”, in Foclóir Gaeilge–Béarla, Dublin: An Gúm, →ISBN
* Gregory Toner, Sharon Arbuthnot, Máire Ní Mhaonaigh, Marie-Luise Theuerkauf, Dagmar Wodtko, editors (2019), “1 dúal”, in eDIL: Electronic Dictionary of the Irish Language
* Gregory Toner, Sharon Arbuthnot, Máire Ní Mhaonaigh, Marie-Luise Theuerkauf, Dagmar Wodtko, editors (2019), “2 dúal”, in eDIL: Electronic Dictionary of the Irish Language
* de Bhaldraithe, Tomás (1959) “dual”, in English-Irish Dictionary, An Gúm
* Finck, F. N. (1899) Die araner mundart [The Aran Dialect] (in German), volume II, Marburg: Elwert’sche Verlagsbuchhandlung, page 72
* “dual”, in New English-Irish Dictionary, Foras na Gaeilge, 2013-2025

## Portuguese
### Pronunciation

* (Brazil) IPA: /duˈaw/ [dʊˈaʊ̯], (faster pronunciation) /ˈdwaw/ [ˈdwaʊ̯]
* (Portugal) IPA: /ˈdwal/ [ˈdwaɫ]
* (Portugal) IPA: /ˈdwal/ [ˈdwaɫ]
** (Southern Portugal) IPA: /ˈdwa.li/
* Rhymes: (Portugal) -al, (Brazil) -aw
* Hyphenation: du‧al

### Adjective

dual m or f (plural duais, not comparable)
* dual (having two elements)

#### Derived terms

* dualidade
* dualmente

## Romanian
### Etymology

Borrowed from French duel, from Latin dualis.

### Noun

dual n (plural duale)
* (grammar) dual

#### Declension
## Scottish Gaelic
### Etymology 1

From Old Irish dúal (“that which belongs or is proper to an individual by nature or descent”), from Proto-Indo-European *dʰewgʰ-.

#### Pronunciation

* IPA: /t̪uəɫ̪/

#### Adjective

dual (comparative duaile)
* hereditary
* usual, natural
    'S dual do phoileasman a bhith amharasach. ― It's natural for a policeman to be suspicious.

#### Noun

dual m (genitive singular duail, plural dualan)
* birthright
    Synonym: còir-bhreith
* due
* something which is natural and/or usual

##### Derived terms

* bu dual do dh'isean an ròin a dhol chun na mara

### Etymology 2

From Old Irish dúal (“tress, lock of hair”), from Proto-Celtic *doklos, from Proto-Indo-European *doḱlos.

#### Noun

dual m (genitive singular duail, plural dualan)
* curl, lock of hair
* plait, strand, braid, or fold
* ringlet

#### Verb

dual (past dhual, future dualidh, verbal noun dualadh, past participle dualte)
* plait, twist
* loop, curl
* fold
* link

### Mutation

Note: Certain mutated forms of some words can never occur in standard Scottish Gaelic. All possible mutated forms are displayed for convenience.

### References

* MacBain, Alexander, Mackay, Eneas (1911) “dual”, in An Etymological Dictionary of the Gaelic Language‎, Stirling, →ISBN, page 145

### Further reading

* Gregory Toner, Sharon Arbuthnot, Máire Ní Mhaonaigh, Marie-Luise Theuerkauf, Dagmar Wodtko, editors (2019), “1 dúal”, in eDIL: Electronic Dictionary of the Irish Language
* Gregory Toner, Sharon Arbuthnot, Máire Ní Mhaonaigh, Marie-Luise Theuerkauf, Dagmar Wodtko, editors (2019), “2 dúal”, in eDIL: Electronic Dictionary of the Irish Language

## Spanish
### Etymology

From Latin duālis.

### Pronunciation

* IPA: /ˈdwal/ [ˈd̪wal]
* Rhymes: -al
* Syllabification: dual

### Adjective

dual m or f (masculine and feminine plural duales)
* dual
* (grammar) dual

#### Derived terms

* dualismo
* dualizar
* dualmente

#### Related terms

* dualidad

### Further reading

* “dual”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8, Royal Spanish Academy [Spanish: Real Academia Española], 2024 December 10