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Dual in Irish (déach): Meaning, Forms, Examples

Other uses of ‘déach’: dual number (noun, masculine)

The Irish for dual is déach: córas déach, a dual system.
Updated October 2026Report a mistake

How to say “dual” in Irish

Irish:
déach
English:
dual
Word type:
adjective
More dual:
níos déiche
Most dual:
is déiche
Plural:
déacha
Pronunciation:
“jayk”  /dʲeːx/

What does “déach” mean?

dual
Having two parts or referring to two; in grammar, the form used for exactly two of something.Also: twofold, double, binary.
Other entries for “déach”

The same spelling has its own page as:

“Déach” after a noun

An Irish adjective comes after its noun. Here is déach after córas (system, masculine), after uimhir (number, feminine) and after a plural.

after a masculine nouncóras déacha dual system
after a feminine nounuimhir dhéacha dual number
after a plural nouncórais dhéachadual systems

séimhiú (the h) the ending

feminine
uimhirnumber
+
déachdual
=
uimhir dhéacha dual number

After a feminine noun the adjective gets a séimhiú, an h after its first letter: uimhir dhéach. After a masculine noun it stays as it is: córas déach.

plural
córaissystems
+
déachadual, plural
=
córais dhéachadual systems

With a plural noun the adjective takes its plural form, déacha. It also gets an h after a plural that ends in a slender consonant: córais dhéacha; after other plurals it does not: uimhreacha déacha.

More dual, most dual, very dual

níosmore
+
déichedual
=
níos déichemore dual
ismost
+
déichedual
=
is déichemost dual

Tá an struchtúr seo níos déiche ná an ceann eile. This structure is more dual in nature than the other one.

more dualníos déichein the past tense: ní ba dhéiche
most dualis déichein the past tense: ba dhéiche
as dual aschomh déach leno change after chomh
very dualan-déachan- lenites, except d, t and s
too dualródhéachró- lenites

“Déach” in a sentence: Irish examples

With a masculine noun, a feminine noun, a plural, a comparison and on its own.

Is córas déach é seo.
This is a dual system.
Bhí uimhir dhéach sa tSean-Ghaeilge.
Old Irish had a dual number.
Tá foirmeacha déacha fós sa teanga.
There are still dual forms in the language.
Tá an struchtúr seo níos déiche ná an ceann eile.
This structure is more dual in nature than the other one.
Tá an fhoirm sin déach.
That form is dual.

Other adjectives in Irish

More everyday Irish adjectives to learn next.

Dual in Irish: frequently asked questions

What is the Irish for dual?

The Irish for dual is déach (pronounced “jayk”). It comes after the noun: córas déach, a dual system; uimhir dhéach, a dual number.

How do you say more dual and most dual in Irish?

níos déiche is more dual and is déiche is most dual. In the past tense they become ní ba dhéiche and ba dhéiche.

Why does déach become dhéach?

After a feminine singular noun an adjective is lenited: it gets an h after its first letter. So uimhir dhéach (a dual number) but córas déach (a dual system), because córas is masculine.

What is the plural of déach?

With a plural noun déach becomes déacha: córais dhéacha, uimhreacha déacha. After a plural that ends in a slender consonant it is lenited as well.

How do you say very dual in Irish?

an-déach. Too dual is ródhéach, and as dual as is chomh déach le.

What is the difference between 'déach' and 'dúbailte'?

'Déach' is a technical word for dual, especially the grammatical dual number, while 'dúbailte' is the everyday word for double, as in 'seomra dúbailte'.

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