The Definite Article in Irish

Overview

Irish has just one definite article — an for singular nouns and na for plural and genitive forms. There is no indefinite article at all, so the word "cat" by itself already means "a cat." This simplicity is balanced by the fact that the article triggers mutations depending on the gender, number, and case of the noun that follows.

At the A1 level, learning how the article behaves is essential because it appears in nearly every sentence. The article interacts with both lenition and eclipsis, making it a practical testing ground for the mutation rules you are learning.

Understanding the article also means learning noun gender, because the mutations that an triggers are different for masculine and feminine nouns. This connection between article and gender is one of the core patterns of Irish grammar.

How It Works

Singular article: an

Context	Rule	Example
Masculine noun (consonant)	No mutation	an fear (the man)
Masculine noun (vowel)	Prefix t-	an t-uisce (the water)
Feminine noun (consonant)	Lenition	an bhean (the woman)
Feminine noun (s + vowel/l/n/r)	Prefix t before s	an tsúil (the eye)
Feminine noun (vowel)	No change	an oíche (the night)

Plural article: na

Context	Rule	Example
Plural nominative (consonant)	No mutation	na fir (the men)
Plural nominative (vowel)	Prefix h	na héin (the birds)
Genitive plural	Eclipsis	na gcailíní (of the girls)

Examples in Context

Irish	English	Note
an fear	the man	Masculine — no mutation
an bhean	the woman	Feminine — lenition
an t-uisce	the water	Masculine vowel — t- prefix
an tsúil	the eye	Feminine s — t prefix
na leabhair	the books	Plural — no mutation
na héin	the birds	Plural vowel — h prefix
cat	a cat	No indefinite article exists
Tá an teach mór.	The house is big.	Basic usage
bainne	milk / some milk	No article = indefinite
doras an tí	the door of the house	Genitive with article

Common Mistakes

Adding an indefinite article

• Wrong: Looking for an Irish word for "a" or "an"
• Right: Just use the bare noun — cat means "a cat"
• Why: Irish has no indefinite article. A noun without an/na is automatically indefinite.

Forgetting lenition with feminine nouns

• Wrong: an bean
• Right: an bhean
• Why: Feminine singular nouns are lenited after an in the nominative case.

Missing the t- prefix before masculine vowels

• Wrong: an uisce
• Right: an t-uisce
• Why: Masculine nouns beginning with a vowel take a t- prefix (with hyphen) after an.

Confusing singular na and plural na

• Wrong: Treating na as always plural
• Right: na also appears in genitive singular feminine — na mná (of the woman)
• Why: The form na serves multiple functions. Context tells you whether it is plural or genitive.

Practice Tips

1. When learning any new noun, always learn it with the article: "an fear" not just "fear." This trains you to remember both the gender and the correct mutation pattern.
2. Sort a list of common nouns into masculine and feminine, then practice placing an before each one. Check whether lenition, t-prefix, or no change applies.

Related Concepts

• Gender of Nouns — determines which mutations the article triggers
• Demonstratives — work together with the article to say "this" and "that"