The Irish Language Grimoire — Nouns and Articles
Irish nouns are gendered and inflected. Every noun is either masculine or feminine, the choice often having little to do with biological sex. Nouns fall into one of five declension classes, each with its own pattern for forming plurals and genitive cases. The article “an” (the) behaves differently with masculine vs feminine nouns, and Irish has no indefinite article: there is no Irish word for “a” or “an” in the English sense.
No indefinite article
This is the simplest fact about Irish nouns and the easiest one to forget: Irish has no equivalent of “a” or “an”. The noun stands alone.
| English | Irish |
|---|---|
| a dog | madra |
| a book | leabhar |
| an apple | úll |
| an idea | smaoineamh |
The Irish word an exists, but it means “the” (definite). The Irish word a exists too, but it is a possessive (“his”, “her”, “their” depending on the mutation that follows) or a relative particle, never an indefinite article.
When a learner writes Tá madra ag an Máire meaning “Mary has a dog”, the an before Máire is wrong: it would mean “the Mary”. The correct sentence is Tá madra ag Máire — no article at all before either noun.
The definite article: an (singular), na (plural)
The singular definite article is an. The plural is na. Both trigger mutations on certain nouns:
| Form | Effect |
|---|---|
| an + masculine noun (nominative) | No mutation in most cases; t- before vowel-initial |
| an + feminine noun (nominative) | Lenition on lenitable consonants |
| an + masculine noun (genitive) | Lenition on lenitable consonants |
| an + feminine noun (genitive) | No mutation in most cases; h- before vowel-initial |
| na + plural noun (nominative) | No mutation; h- before vowel-initial |
| na + plural noun (genitive) | Eclipsis on eclipsable consonants |
Examples:
- fear (man, masc) → an fear (the man)
- bean (woman, fem) → an bhean (the woman — lenited)
- uisce (water, masc) → an t-uisce (the water — t- prefix)
- oíche (night, fem) → an oíche (the night — no prefix)
Gender
Irish noun gender is often unpredictable from meaning. Some rules of thumb:
- Most nouns ending in -óg, -eog, -óir (the agent suffix) — varies; check
- Most nouns ending in -acht, -íocht, -int — feminine
- Most nouns ending in a broad consonant — masculine
- Most loanwords ending in -a, -e — feminine
- Many small / common nouns — irregular
A practical approach: when you learn a noun, learn it with its article. An fear (masc), an bhean (fem). After enough exposure, the gender becomes part of how you remember the word.
The five declension classes
Each class has its own pattern for forming the plural and the genitive singular. The five classes are not equally common; the first two cover the majority of nouns.
| Class | Typical ending | Plural pattern | Example |
|---|---|---|---|
| 1st | masculine, broad consonant | slenderise + plural ending | fear → fir (men) |
| 2nd | feminine, slender consonant | add -a or -e | bean → mná (irregular); cailín → cailíní |
| 3rd | masculine OR feminine, ends in -óir, -úir, -eoir | add -í | múinteoir → múinteoirí (teachers) |
| 4th | nouns ending in vowel or -ín | add -í or -eanna | bus → busanna; cailín → cailíní |
| 5th | irregular (mostly old monosyllables) | various | teach → tithe (houses); lá → laethanta (days) |
The genitive singular form varies by class. See the Genitive Case page for the genitive system in detail.
The article and the noun together
The clean way to learn how a noun behaves in practice is to memorise four forms together:
1. fear — the noun bare (nominative singular) 2. an fear — with the article 3. fir — the plural 4. an fhir — genitive singular (for masculine class-1 nouns, lenition + slenderisation)
The Grimoire’s vocabulary entries include gender, plural, and genitive where they are known. The translator uses them to inflect the noun when the rule engine needs the right form.