The declension of Irish nouns, the definite article, and the adjectives is discussed on this page (for pronouns, see Irish Grammar).



Nouns in Irish are divided into two genders, masculine and feminine; the Old Irish neuter gender no longer exists. While gender should be learned when the specific noun is learned, there are some guidelines that can be followed:

Generally, nouns in singular form ending with broad consonants are masculine, while those ending in a slender consonant are feminine.

There are some exceptions, mostly dealing with specific endings and suffixes; for example, words ending in -óir/-eoir and -ín (with a slender /ɾʲ/ and /nʲ/ respectively) are categorically masculine, while words ending in -óg/-eog (with a broad /ɡ/) are feminine. This leads to some unexpected gender assignments, such as gasóg "boy scout" being feminine, and cailín "girl" masculine (the diminutive -ín suffix is always masculine irrespective of the noun it applies to).


Irish has four cases: common (usually called the nominative, but it covers the role of the accusative as well), vocative, genitive, and the dative or prepositional case.


The nominative is used in the following functions:

  1. Sentence subject
    Tá an cat ag ól. "The cat is drinking."
  2. Sentence object
    Bhris Seán an fhuinneog. "Seán broke the window."
  3. Predicate of the copula
    Is amadán é. "He is an idiot."
  4. Object of the prepositions gan "without", go dtí "(up) to" and mar "like, as".
    gan an t-airgead "without the money"
    go dtí an t-am "(up) to the time"
    mar an chearc "like the hen"


The vocative is used in direct address, and is always preceded by the particle a, which triggers lenition (the vocative particle is not pronounced before a vowel sound). The first declension is the only declension in which the vocative is distinct from the nominative.


The genitive indicates possession and material of composition:

The object of a verbal noun also requires the genitive:

The object of a compound preposition is in the genitive. Formally, these prepositions are actually prepositional phrases.


The dative/prepositional is used as the object of most simple prepositions except gan and go dtí. In standard language, the dative is almost always identical to the nominative. Some dialects, however, have distinct standalone datives in the second and fifth declensions. In the standard language, only two words Éire ("Ireland") and fiche ("twenty") have distinct datives - Éirinn and fichid, respectively. They are also found in certain fixed phrases with nouns of the second declension, such as os cionn ("above", lit. "over head" – cionn is the old dative of ceann ("head")).


There are five recognized declensions in Irish. The makeup of the declensions depends on three factors:

  1. the gender of the noun
  2. the formation of the genitive singular
  3. relation of genitive singular to nominative plural

The following chart describes the characteristics of each declension class:

Nom. sing. ends with: Gen. sing. ends with: Gender
First declension Broad consonant Slender consonant Masculine
Second declension Broad or slender consonant -e/-í Feminine with rare exceptions
Third declension Slender or broad consonant -a Masculine or feminine
Fourth declension Vowel or -ín (no change) Masculine or feminine
Fifth declension Vowel or slender consonant Broad consonant Mostly feminine


The first declension is made up of masculine nouns. The nominative singular ends in a broad consonant, which is made slender in the genitive singular. The most common formation of the plural has the opposite pattern: the nominative ends in a slender consonant, the genitive in a broad consonant (these plurals are known as weak plurals in comparison with strong plurals which maintain identical endings for all cases in the plural). The dative is identical to the nominative in both numbers, although an obsolete dative plural in -aibh is still sometimes encountered in old-fashioned literary style.

bád "boat" Singular Plural
Nominative bád /bˠaːd̪ˠ/ báid /bˠaːdʲ/
Vocative a bháid waːdʲ/ a bháda waːd̪ˠə/
Genitive báid /bˠaːdʲ/ bád /bˠaːd̪ˠ/
Dative bád /bˠaːd̪ˠ/ báid (obsolete bádaibh)

When /x/ in the gen. sing. and nom. pl. of a polysyllabic word is made slender, it also becomes voiced, thus:

marcach "a horseman" Singular Plural
Nominative marcach /mˠaɾˠkəx/ marcaigh /mˠaɾˠkəj/
Vocative a mharcaigh


a mharcacha waɾˠkəxə/
Genitive marcaigh


marcach /mˠaɾˠkəx/
Dative marcach


marcaigh (obsolete marcachaibh)

Some nouns undergo a vowel change before the slender consonant of the genitive singular/nominative plural:

Many words of this declension form the plural with one of the endings -(a)í, -ta, -tha, -anna. These are known as "strong plural" endings, which means the plural is identical in all cases in the standard language. Some examples:

Some nouns have a weak plural (a plural where the genitive is different from the nominative, and is identical to the form of the nominative singular) in -a:

Other strong plural formations are found in:


The second declension is made up of mostly feminine nouns, and features a nominative singular form that can end in either a broad or a slender consonant. The genitive singular ends in a slender consonant followed by -e. The most common plural form has a broad consonant followed by -a in the nominative, and a broad consonant alone in the genitive. The vocative has the same endings as the nominative, as does the dative in standard language.

bróg "shoe" Singular Plural
Nominative bróg /bˠɾˠoːɡ/ bróga /ˈbˠɾˠoːɡə/
Vocative a bhróg wɾˠoːɡ/ a bhróga ˈwɾˠoːɡə/
Genitive bróige /ˈbˠɾˠoːɟə/ bróg /bˠɾˠoːɡ/
Dative bróg /bˠɾˠoːɡ/
 (obsolete/dialectal bróig)
bróga /ˈbˠɾˠoːɡə/
 (obsolete brógaibh)
deoir "tear" Singular Plural
Nominative/Dative deoir /dʲoːɾʲ/ deora /ˈdʲoːɾˠə/
Vocative a dheoir joːɾʲ/ a dheora ˈjoːɾˠə/
Genitive deoire /ˈdʲoːɾʲə/ deor /dʲoːɾˠ/

In Connacht Irish and Waterford Irish it is often the case that all nouns of the second declension in the nom. sg. end with a slender consonant (e.g. bróig "a shoe").

In some Munster varieties as well as the old literary language, the dative singular is distinct and ends in a slender consonant alone (in effect the dative sg. is formed by dropping the -e from the genitive sg.), e.g. i mo bhróig "in my shoe" (historically, nominative forms like bróig are descended from the old dative).

When /x/ in the gen. sing. is made slender, it is also voiced, so /x/ > /ç/ > /j/. /əjə/ becomes /iː/, and is written -(a)í.

girseach "little girl" Singular Plural
Nominative/Std. dative girseach /ˈɟɪɾˠʃəx/ girseacha /ˈɟɪɾˠʃəxə/
Vocative a ghirseach ˈjɪɾˠʃəx/ a ghirseacha ˈjɪɾˠʃəxə/
Genitive girsí /ˈɟɪɾˠʃiː/ girseach /ˈɟɪɾˠʃəx/
Nonstandard Dative girsigh /ˈɟɪɾˠʃiː/ (obsolete/dialectal) girseachaibh /ˈɟɪɾˠʃəxəvʲ/ (obsolete)

Many words in this declension form a strong plural with one of the endings -t(h)a,-te, -(e)acha or -eanna:

Other strong plural formations are found in:


The third declension is made up of masculine and feminine nouns. It is characterized by the genitive singular in -a. The majority of nouns in this class form the plural in -(a)í. The final consonant of the stem may be broad or slender: it retains its quality in the plural, but is always broad in the genitive singular.

Singular Plural
Nominative/Vocative/Dative broad or slender cons. -(a)í
Genitive broad cons. + -a -(a)í
bádóir (m.) "boatsman" Singular Plural
Nominative/Dative bádóir /ˈbˠaːd̪ˠoːɾʲ/ bádóirí /ˈbˠaːd̪ˠoːɾʲiː/
Vocative a bhádóir ˈwaːd̪ˠoːɾʲ/ a bhádóirí ˈwaːd̪ˠoːɾʲiː/
Genitive bádóra /ˈbˠaːd̪ˠoːɾˠə/ bádóirí /ˈbˠaːd̪ˠoːɾʲiː/
rás (m.) "race" Singular Plural
Nominative/Dative rás /ɾˠaːsˠ/ rásaí /ˈɾˠaːsˠiː/
Vocative a rás ɾˠaːsˠ/ a rásaí ˈɾˠaːsˠiː/
Genitive rása /ˈɾˠaːsˠə/ rásaí /ˈɾˠaːsˠiː/

Feminine nouns in -áint or -úint lose their ⟨t⟩ in the gen. sg.; those in -irt have -⟨th⟩- instead of -⟨t⟩- in the gen. sg.

Many words in this declension form the plural with one of the endings -anna or -acha:

Some words in Munster Irish also have a separate dative form:


The fourth declension is made up of masculine and feminine nouns. It is characterized by a genitive singular that is identical in form to the nominative/vocative/dative singular. The singular may end in a vowel or a consonant (usually the diminutive suffix -ín). The most common plural ending is -(a)í.

Singular Plural
All cases Vowel or consonant (usually -ín) -(a)í
balla (m.) "wall" Singular Plural
Nominative/Genitive/Dative balla /ˈbˠal̪ˠə/ ballaí /ˈbˠal̪ˠiː/
Vocative a bhalla ˈwal̪ˠə/ a bhallaí ˈwal̪ˠiː/
comhairle (f.) "(piece of) advice" Singular Plural
Nominative/Genitive/Dative comhairle /ˈkoːɾˠl̠ʲə/ comhairlí /ˈkoːɾˠl̠ʲiː/
Vocative a chomhairle ˈxoːɾˠl̠ʲə/ a chomhairlí ˈxoːɾˠl̠ʲiː/
cailín (m.) "girl" Singular Plural
Nominative/Genitive/Dative cailín /ˈkalʲiːnʲ/ cailíní /ˈkalʲiːnʲiː/
Vocative a chailín ˈxalʲiːnʲ/ a chailíní ˈxalʲiːnʲiː/

Many words of this declension form the plural with the following endings -tha/-t(h)e, -((e)a)nna or -((e)a)cha:

Other strong plural formations are found in:

One noun in this class has a weak plural:


The fifth declension is made up mostly of feminine nouns and is characterized by a genitive singular that ends in a broad consonant that has been added to the nominative/vocative/dative singular. The most common plural is strong, formed by adding -a to the genitive singular.

Singular Plural
Nominative/Vocative/Dative Vowel or slender consonant Gen. sg. + -a
Genitive broad consonant Gen. sg. + -a
pearsa "person" Singular Plural
Nominative/Dative pearsa /ˈpʲaɾˠsˠə/ pearsana /ˈpʲaɾˠsˠən̪ˠə/
Vocative a phearsa ˈfʲaɾˠsˠə/ a phearsana ˈfʲaɾˠsˠən̪ˠə/
Genitive pearsan /ˈpʲaɾˠsˠən̪ˠ/ pearsana /ˈpʲaɾˠsˠən̪ˠə/
cathair "city" Singular Plural
Nominative/Dative cathair /ˈkahəɾʲ/ cathracha /ˈkaɾˠəxə/
Vocative a chathair ˈxahəɾʲ/ a chathracha ˈxaɾˠəxə/
Genitive cathrach /ˈkaɾˠəx/ cathracha /ˈkaɾˠəxə/

In some Munster Irish varieties as well as the old literary language, the dative singular is distinct and ends in a slender consonant (in effect the dative sg. is formed by palatalizing the genitive sg.), for example, do phearsain "to a person", ón gcathraigh "from the city". In Éire, Éireann "Ireland" the dative Éirinn is still used in the standard language.

Some words form the genitive singular by changing the final consonant of the nominative singular to broad. The plural is then strong -eacha.

Other strong plural formations are found in:

Some nouns have weak plurals; here the genitive singular and genitive plural have the same form:

Verbal nouns

The most productive verbal nouns end with -(e)adh (1st conjugation) or -(i)ú (2nd conjugation). These originally belonged to the third declension, but synchronically are best regarded as separate declensions.

The 1st conjugation verbal noun in -(e)adh has a genitive singular in -te/-ta and a plural in -t(a)í.

The 2nd conjugation verbal noun in -(i)ú has a genitive singular in -(a)ithe and a plural in -(u)ithe. These endings are pronounced the same regardless of the spelling distinction.

Irregular nouns

The following nouns are declined irregularly:


The definite article has two forms in Irish: an and na. Their distribution depends on number, case, and gender, and they trigger mutation partly on the basis of the initial sound of the following word. Each entry of the table gives an example of one noun starting with a consonant and one with a vowel.

Singular Plural
Masculine Feminine both genders
Nominative an cat
an t-éan
an bhróg
an eaglais
(do) na cait
(leis) na héin
Dative (i) den chat
san éan
don bhróg
den eaglais
Dative (ii) ag an gcat
ag an éan
faoin mbróg
tríd an eaglais
Genitive an chait
an éin
na bróige
na heaglaise
na gcat

na n-éan

Dative (i) is used with all prepositions in Ulster usage; in Munster and the standard language it is used only with den "from the", don "to the", and sa(n) "in the" but there are also Munster dialects in which only sa(n) triggers lenition and den and don eclipse, as with every other article-preposition compound. In Connacht sa(n) eclipses whereas den and don lenite. Dative (ii) is used outside Ulster with other prepositions.

The article never mutates a following ⟨d⟩ or ⟨t⟩ in the singular, and ⟨s⟩ is lenited to ⟨ts⟩ (pronounced [t̪ˠ, tʲ]) rather than the usual ⟨sh⟩. ⟨s⟩ furthermore lenites in both dative (i) and (ii) in the singular with feminine nouns but does not lenite at all with masculine nouns.

It does, however, eclipse ⟨t⟩ and ⟨d⟩ in Munster dialects and forms like "ag an ndoras" instead of the usual pattern "ag an doras", which is used in all other dialects, do occur.

There is no indefinite article in Irish, so depending on context cat can mean "cat" or "a cat".


Almost all adjectives in Irish can be used either predicatively or attributively. A predicative adjective is one that forms a part of the predicate, like red in the sentence The car is red. An attributive adjective directly modifies a noun, as in the red car.

A predicate adjective in Irish does not inflect:

A predicate adjective expressing a value judgment is often preceded by the particle go. This particle attaches ⟨h⟩ to a following vowel.

In Ulster, go is not generally used in these cases.

An attributive adjective mostly follows the noun and is inflected:

There are four classes of declension of adjectives in Irish, which correspond to the first four declensions of nouns:

Nom. sg. ends with: Gen. sg. masc. ends with: Gen. sg. fem. ends with:
1st decl. broad cons. slender consonant slender consonant + -e
2nd decl. slender cons. slender consonant slender consonant + -e
3rd decl. slender cons. (mostly -úil) slender consonant broad consonant + -a
4th decl. vowel = nom. sg. = nom. sg.

First declension

bocht "poor" Masc. sg. Fem. sg. Plural
Nominative bocht bhocht b(h)ochta
Genitive bhoicht boichte bocht(a)
bacach "lame" Masc. sg. Fem. sg. Plural
Nominative bacach bhacach b(h)acacha
Genitive bhacaigh bacaí bacach(a)

Second declension

ciúin "quiet" Masc. sg. Fem. sg. Plural
Nominative ciúin chiúin c(h)iúine
Genitive chiúin ciúine ciúin(e)

Third declension

misniúil "brave" Masc. sg. Fem. sg. Plural
Nominative misniúil mhisniúil m(h)isniúla
Genitive mhisniúil misniúla misniúil, -úla
cóir "just" Masc. Sg. Fem. Sg. Plural
Nominative cóir chóir c(h)óra
Genitive chóir córa cóir, córa

Fourth declension

This declension does not inflect, but it does mutate.

crua "hard" Masc. sg. Fem. sg. Plural
Nominative crua chrua c(h)rua
Genitive chrua crua crua

Irregular adjectives

Masc. sg. nom. & gen. Fem. sg. nom. Fem. sg. gen. Pl. nom./gen. Gloss
álainn álainn áille áille "beautiful"
breá bhreá breátha b(h)reátha "fine"
deacair dheacair deacra d(h)eacra "difficult"
gearr ghearr giorra g(h)earra "short"
socair shocair socra s(h)ocra "still"
tapaidh thapaidh thapaí t(h)apaí "fast"
te the te t(h)eo "hot"
tirim thirim tirime t(h)iorma "dry"


Irish adjectives have a comparative form equivalent to the comparative and superlative in English. The comparative does not undergo inflexion and is the same as the feminine singular genitive in regular and many irregular adjectives.

Regular formation

Base form Comparative form Gloss
álainn áille "beautiful/more beautiful"
bacach bacaí "lame/lamer"
bocht boichte "poor/poorer"
ciúin ciúine "quiet/quieter"
cóir córa "just/more just"
crua crua "hard/harder"
deacair deacra "difficult/more difficult"
gearr giorra "short/shorter"
misniúil misniúla "brave/braver"
socair socra "still/stiller"
tapaidh tapaí "fast/faster"
tirim tirime "dry/drier"

Irregular forms

Base form Comparative form Gloss
beag "small/smaller"
breá breátha "fine/finer"
dócha dóichí "possible/more possible"
fada faide "long/longer"
fogus foisce "near/nearer"
furasta fusa "easy/easier"
iomaí lia "many/more"
ionúin ansa "beloved, dear/more beloved, dearer"
maith fearr "good/better"
olc measa "bad/worse"
te teo "hot/hotter"
tréan tréine or treise "strong/stronger"
mór "big/bigger"

Syntax of comparison

There are two constructions to express the comparative:

1) Copula + comparative form + subject + ("than") + predicate. The preterite of the copula causes lenition, while the present tense does not.

2) níos/ní ba/ní b’ + comparative + + predicate. Níos is used if the sentence is in the present or future tense.

Ní ba/ní b’, which triggers lenition, is used if the sentence is in the past tense. Ní b’ is used before words starting with vowels and ní ba before those starting with consonants.

A superlative is expressed as a relative clause: noun + is/ba/ab + comparative form.