The Genitive Case in Irish

Overview

The genitive case is one of the most distinctive features of Irish grammar. It is used to show possession, after verbal nouns, and after certain prepositions. When a noun is in the genitive case, its form often changes — through slenderization, broadening, suffix changes, or a combination — and these changes can seem daunting at first. However, the genitive case follows patterns based on noun declension type.

In English, possession is shown with "'s" or "of": "the door of the house" or "the house's door." In Irish, the possessed noun comes first and the possessor follows in the genitive case: doras an tí (door of the house), where teach (house) changes to tí in the genitive. The definite article also changes form in the genitive.

The genitive is also triggered after verbal nouns when they have a definite object: ag léamh an leabhair (reading the book), where leabhar becomes leabhair. This makes the genitive case one of the most frequently encountered grammatical features in Irish.

How It Works

When to Use the Genitive

Context	Example	English
Possession	doras an tí	the door of the house
After verbal nouns	ag léamh an leabhair	reading the book
After compound prepositions	ar feadh na hoíche	for the whole night
After quantity words	a lán airgid	a lot of money

Common Genitive Changes (Masculine Nouns)

Nominative	Genitive	Change	English
an fear	an fhir	slenderization + lenition	the man → of the man
an leabhar	an leabhair	slenderization	the book → of the book
an bád	an bháid	slenderization + lenition	the boat → of the boat
an teach	an tí	irregular	the house → of the house
an cnoc	an chnoic	slenderization + lenition	the hill → of the hill

Common Genitive Changes (Feminine Nouns)

Nominative	Genitive	Change	English
an bhean	na mná	irregular	the woman → of the woman
an tír	na tíre	add -e	the country → of the country
an scoil	na scoile	add -e	the school → of the school
an oíche	na hoíche	h-prefix after na	the night → of the night
an Ghaeilge	na Gaeilge	article change	Irish → of Irish

The Article in the Genitive

Gender	Nominative Article	Genitive Article
Masculine	an (+ sometimes t-/h-)	an + lenition
Feminine	an (+ lenition)	na (+ h- before vowels)
Plural	na	na + eclipsis

Examples in Context

Irish	English	Note
doras an tí	the door of the house	teach → tí (irregular)
ag léamh an leabhair	reading the book	leabhar → leabhair
hata na mná	the woman's hat	bean → mná (irregular)
barr an chnoic	the top of the hill	cnoc → chnoic
muintir na tíre	the people of the country	tír → tíre
ag déanamh na hoibre	doing the work	obair → oibre
lár an bhaile	the centre of the town	baile → bhaile
i rith an lae	during the day	lá → lae
mac an fhir	the man's son	fear → fhir
bun na scoile	the bottom of the school	scoil → scoile

Common Mistakes

Forgetting to change the noun form

• Wrong: doras an teach
• Right: doras an tí
• Why: After another noun in a possessive construction, the second noun must be in the genitive case, which often involves a form change.

Using the wrong article in the genitive

• Wrong: doras an tí is correct, but hata an mná is wrong
• Right: hata na mná
• Why: Feminine nouns in the genitive use the article na, not an.

Forgetting the genitive after verbal nouns

• Wrong: ag léamh an leabhar
• Right: ag léamh an leabhair
• Why: When a verbal noun has a definite object, that object goes in the genitive case.

Usage Notes

The genitive case is more strictly maintained in written and formal Irish than in casual speech. In some dialects, particularly in Connacht, the genitive forms are sometimes simplified in everyday conversation. However, common genitive phrases like doras an tí, muintir na tíre, and ag léamh an leabhair are used universally and should be learned as fixed expressions even before you master the full genitive system.

Practice Tips

1. Start with the most common genitive phrases and learn them as set expressions: lár an bhaile (town centre), doras an tí (the door of the house), barr an chnoic (the hilltop).
2. Practice the genitive after verbal nouns by describing what you are doing: ag léamh an leabhair (reading the book), ag déanamh na hoibre (doing the work).

Related Concepts

• Gender of Nouns — the gender system that determines genitive article forms
• The Dative Case — another case found after prepositions
• Abstract Vocabulary and Nominalization — abstract nouns that often appear in genitive constructions
• Vocative Case and Special Forms — the case used for direct address