Cases

In Irish, nouns change their form depending on their grammatical function in a sentence, such as being the subject, the object, or showing possession. These different forms are called cases, or tuisil. While modern Irish grammar officially recognises a “common case” for the subject and object, it is helpful for learners to understand the traditional five cases, as they have distinct uses and trigger different mutations.

The five cases are:

1. Nominative (an tuiseal ainmneach): The subject of a sentence.
2. Genitive (an tuiseal ginideach): Shows possession or relationship.
3. Dative (an tuiseal tabharthach): Used after most prepositions.
4. Accusative (an tuiseal cuspóireach): The direct object of a sentence.
5. Vocative (an tuiseal gairmeach): Used for direct address.

The Nominative Case

The nominative case (an tuiseal ainmneach) is the basic form of a noun, the one you will find in a dictionary. It is primarily used for the subject of a sentence.

Usage

The nominative is used in several key situations:

• As the subject of a sentence:
  • Itheann an fear. - The man eats.
• As the subject and predicate noun in a copula sentence:
  • Is é an dochtúir an fear. - The man is the doctor.
• As an absolute nominative to change word order (left or right dislocation):
  • An fear a chonaic mé inné, bhí sé ag dul abhaile. - The man I saw yesterday, he was going home.
• As a “functional genitive” where the noun has a genitive role but keeps its nominative form. This is covered in the genitive section.
• After certain prepositions: The nominative is used after seachas, go dtí, and murach.
  • These prepositions evolved from verbs, so the noun following them was originally a subject.
• As a qualitative nominative (an t-ainmneach cáilíochtúil) after adjectives, often in comparative forms, to describe a quality.
  • an fear is mó cáil - the man of greatest fame (literally: “the man who-is greater fame”)
  • an té is ard glór - the one with a loud voice (literally: “the one who-is high voice”)
  • bean chomh maith ciall agus tuiscint leat - a woman of as good understanding and comprehension as you

Nominative Singular

The nominative singular (an t-ainmneach uatha) is the base form of the noun.

Nominative Plural

The nominative plural (an t-ainmneach iolra) has various endings depending on the noun’s declension.

Nominative Dual

The dual form (an t-ainmneach déach) is used with the number two (dhá).

The Genitive Case

The genitive case (an tuiseal ginideach) is primarily used to show possession, origin, or a relationship between two nouns, similar to “‘s” or “of” in English.

Usage

The genitive has a wide range of uses.

• As an attribute of another noun: The genitive noun always follows the noun it modifies.
  • Possession: teach an fhir - the man’s house
  • Origin: mac Sheáin - Seán’s son
  • Material: teach adhmaid - a wooden house (a house of wood)
  • Content: bosca chíste - a biscuit box
  • Description: lá Nollag - Christmas Day
  • Purpose: bróg cailín - a girl’s shoe
  • Measurements: leanbh bliana - a one-year-old child
  • Apposition: baintreach fir - a widower (literally: “a widow of a man”)
• Genitive of action:
  • Objective genitive: The genitive indicates the object of a transitive action.
    • grá Dé - the love for God
  • Subjective genitive: The genitive indicates the subject of an intransitive action.
    • imeacht na traenach - the departure of the train
• As the object of a verbal noun:
  • A definite noun after a verbal noun is in the genitive: Tá sé ag déanamh na hoibre. - He is doing the work.
  • An indefinite noun with no attribute is also in the genitive: Tá sé ag cur báistí. - It is raining.
• After certain prepositions: The genitive is required after trasna, chun, cois, timpeall, fearacht, and tar éis.
  • trasna an ghoirt - across the field
• After compound prepositions that contain a noun, like ar aghaidh.
  • ar aghaidh an tí - in front of the house
• After quantifiers like mórán (much), beagán (little), neart (plenty), roinnt (some), dóthain (enough), cuid (part).
  • roinnt bainne - some milk
  • a cuid gruaige - her hair (literally: “her share of hair”)

Chains of Nouns (Genitive Sequences)

When two or more nouns appear in a genitive relationship, the rules can become complex. The key is to identify which nouns form a single semantic unit.

Double Genitive

A true double genitive, where two consecutive nouns both take the genitive form, is common when at least one of the genitives is indefinite and helps form a compound-like expression.

• All nouns indefinite:
  • scoil phobail chathrach - a city community school
• First genitive is indefinite, second is definite:
  • fear ionaid an rí - the king’s representative (where fear ionaid means “representative”)
  • mála scoile an bhuachalla - the boy’s school bag
• Second genitive is indefinite, first is definite:
  • seol an bháid adhmaid - the sail of the wooden boat

The Functional Genitive

More commonly, when a chain of nouns occurs, Irish avoids a double genitive form by using a “functional genitive”. Here, a noun is in a genitive relationship but keeps its nominative form. Only the final noun in the chain takes the genitive form.

This happens when a noun already has a definite genitive attribute (mac Sheáin, Poblacht na hÉireann), and this entire unit becomes the attribute of another noun.

• The noun in the functional genitive is always lenited (if possible).

• Only the last noun takes the genitive ending.

• teach mhac Sheáin - the house of Seán’s son (Here, mac is functionally genitive but formally nominative, so it is lenited to mhac. Seáin is the final noun and takes the genitive form.)

• stair Phoblacht na hÉireann - the history of the Republic of Ireland

• seomra fhear an tí - the room of the man of the house

This can create long chains, where each intermediate noun is in the functional genitive (nominative form + lenition).

• fuinneog theach mhac Sheáin - the window of the house of Seán’s son
• dath fhuinneog theach mhac Sheáin - the colour of the window of the house of Seán’s son

Avoidance of the Genitive Form

In several situations, a noun that is functionally genitive remains in its nominative form.

• After quantifiers like roinnt or cuid.
  • Tá sé ag ól roinnt bainne. - He is drinking some milk.
• As the object of a verbal noun when the noun has a further attribute.
  • Tá sé ag léamh leabhar maith. - He is reading a good book.
• With numbers, except after aon (one).
  • teach an dara fear - the house of the second man
  • stampa cúig scilling - a 5-shilling stamp
• For feminine personal names when they have an adjective or surname.
  • teach Bhríd Rua - the house of red-haired Bríd (but: teach Bhríde)
• After cúpla (a couple) and cé mhéad (how many).
  • Tá sé ag ól cúpla deoch. - He is drinking a couple of drinks.

Partitive Genitive and Partitive Dative

To express a part of a whole, Irish uses two different structures.

• Partitive Genitive: Used with indefinite nouns.
  • roinnt airgid - some money (a share of money)
  • ceathrú úill - a quarter of an apple
• Partitive Dative: Used with definite nouns, employing the preposition de.
  • cuid den airgead - a part of the money
  • roinnt de na fir - some of the men

This distinction is important. Compare:

• cuid an airgid - the part of the money (genitive, definite)
• cuid den airgead - a part of the money (dative, indefinite)

Definite and Indefinite Genitives

• A definite genitive attribute (e.g., a noun with an article, a proper name, a possessive pronoun) makes the entire phrase definite. The head noun cannot take its own article.
  • teach an dochtúra - the doctor’s house (not “a” doctor’s house)
  • teach Sheáin - Seán’s house
• To say “a doctor’s house”, you must use a prepositional phrase.
  • teach don dochtúir - a house for the doctor
  • dán le Goethe - a poem by Goethe
  • rang de chuid an mhúinteora - a class of the teacher’s
• An indefinite genitive attribute often forms a compound-like expression with the head noun. The article, if used, comes before the head noun.
  • scian phóca - a pocket knife
  • an scian phóca - the pocket knife

Genitive Singular

The genitive singular (an ginideach uatha) is formed in different ways depending on the noun’s declension group.

Genitive Plural

The genitive plural (an ginideach iolra) has several common forms:

• Same as Nominative Singular: For nouns with a “weak” plural (most 1st declension nouns).
  • an fear (the man) -> na bhfear (of the men)
  • an bhróg (the shoe) -> na mbróg (of the shoes)
• Same as Nominative Plural: For nouns with a “strong” plural (most 3rd, 4th, and 5th declension nouns).
  • na cailíní (the girls) -> na gcailíní (of the girls)
• Same as Genitive Singular: For some 5th declension nouns.
  • an charad (of the friend) -> na gcarad (of the friends)
• Independent Form: For some irregular nouns.
  • bean (woman) -> ban (of women)

Mutations in the Genitive

• Indefinite nouns in the genitive are lenited based on the gender and number of the noun they follow, similar to adjectives.
• Definite nouns in the genitive follow the mutation rules of the word that makes them definite (the article, a possessive pronoun). If it’s a proper noun without an article, it is lenited.

The Dative Case

The dative case (an tuiseal tabharthach) is also known as the prepositional case, as its primary function is to follow most simple prepositions. In modern standard Irish, its form is almost always identical to the nominative.

Usage

• After most simple prepositions: ag, ar, as, de, do, faoi, i, le, ó, roimh, trí, etc.
• As an indirect object, always with a preposition (usually do).
  • Tugaim an leabhar don bhean. - I give the book to the woman.
• Dative of advantage (do) or disadvantage (ar):
  • Rinne mé duit é. - I did it for you.
  • Bhris mé an claí ar an bhfear. - I broke the man’s fence (to his disadvantage).
  • Múchadh an tine orm. - The fire went out on me.
• Possessive dative with le or do for indefinite relationships.
  • deartháir le Seán - a brother of Seán’s
  • cara dom - a friend of mine
• Partitive dative with de to indicate a part of a definite whole.
  • cuid den obair - part of the work
  • beirt de na mná - two of the women
• Dative of the agent to show the logical subject in certain constructions.
  • Is as Doire dom. - I am from Derry.
  • Tá an litir le scríobh agam. - The letter is to be written by me. / I have to write the letter.

Independent Dative Forms

While the dative form is usually the same as the nominative today, a few distinct dative singular forms survive in the standard language, especially from the 2nd declension.

Some older forms also survive in fixed phrases, like os cionn (above) from ceann (head).

Dative Singular

Historically, the dative singular of 2nd declension nouns was formed by palatalisation (making the final consonant slender).

• bróg -> bróig
• teach -> tigh

The dative of 5th declension nouns like Éire was formed by palatalising the genitive (Éireann -> Éirinn). As noted earlier, these historical dative forms are now often used as the standard nominative in some dialects.

Dative Plural

The historical dative plural was formed with the ending -ibh. This ending is cognate with the Latin -ibus.

Mutations in the Dative

Mutations after prepositions depend on the specific preposition and whether an article is present.

• Without an article: Some prepositions cause lenition (ar, de, do, ó), i causes eclipsis, and others cause no mutation (ag, as, le).
• With the singular article: The rules vary by dialect. The standard allows for either lenition or eclipsis after many prepositions (ar an mbád or ar an bhád). However, after den, don, and san, lenition is standard.

The Accusative Case

The accusative case (an tuiseal cuspóireach) is used for the direct object of a sentence. In Modern Irish, its form is always identical to the nominative. You can only distinguish it by its function and position in the sentence.

Usage

• As the direct object of a verb:
  • Chonaic mé an fear. - I saw the man.
• As the object of a verbal noun in an infinitive construction with a.
  • an fear a fheiceáil - to see the man
• In adverbial expressions of time and place:
  • Bhí mé ann an oíche sin. - I was there that night.
  • Chuaigh mé an bóthar. - I went the road.
• For measurements of size, weight, age, etc.
  • Tá sí seacht mbliana d’aois. - She is seven years old.
• After the prepositions ach, gan, idir, mar, and ná.

The Vocative Case

The vocative case (an tuiseal gairmeach) is used for direct address, when calling or speaking to someone or something.

Usage

• Nouns in the vocative are always preceded by the particle a, which causes lenition.
  • Dia dhuit, a Sheáin! - Hello, Seán!
• The particle a is unstressed. For a more emphatic address, ó can be added.
  • A Sheáin, ó! - Oh, Seán!
  • Ó, a Dhia! - O God!
• Possessive pronouns like “my” are not used. a chara means “My friend!”. The main exception is in the Lord’s Prayer: Ár nAthair (Our Father).

Vocative Singular

• 1st Declension: The vocative form is the same as the genitive singular.
  • fear (man) -> a fhir!
• 2nd-5th Declension: The vocative form is the same as the nominative singular.
  • cailín (girl) -> a chailín!

Adjectives in the Vocative Singular:

• Adjectives are always lenited.
• After a masculine noun, the adjective takes its genitive singular form.
  • a fhir mhóir! - big man!
• After a feminine noun, the adjective takes its nominative singular form.
  • a bhean mhór! - big woman!

Exceptions

• In names, Ó becomes Uí: a Phóil Uí Shé! (Paul O’Shea!)
• In names, Mac becomes Mhic: a Sheáin Mhic Mhathúna! (Seán MacMahon!)
• mac (son) -> a mhic!
• Mícheál -> a Mhíchíl!

Vocative Plural

• Weak Plural: The vocative is the nominative singular + a.
  • fir (men) -> a fheara!
• Strong Plural: The vocative is the same as the nominative plural.
  • buachaillí (boys) -> a bhuachaillí!

Adjectives in the Vocative Plural:

• Adjectives are not lenited and take their nominative plural form.
  • a fheara Gearmánacha! - German men!

Address without the Vocative Form

In some cases, the vocative particle a is used, but the noun keeps its nominative form.

• With terms of endearment or metaphors:
  • a stór! - my treasure/darling!
• With collective nouns:
  • a phobal! - People!
• When a definite genitive follows:
  • a fhear an tí! - Master of the house!
• In multi-word titles:
  • a Cheann Comhairle! - Chairman!