The Genitive in Irish Grammar

When people first start studying the Irish language, they very quickly run up against concepts they’ve never encountered before. For many, the most daunting is a special form of the noun known as “the genitive case.”

There are several ways to form the genitive in Irish, depending on such factors as the gender, number, and declension of the noun.  That’s really beyond the scope of a single blog post.  If you’re learning Irish, your teacher, book, or program should help with that.

What this post will discuss, rather, is some of the ways the genitive is used in the Irish language, and why it’s so important to get a handle on it.

First, a couple of terms

It’s impossible to discuss grammar without using a few specialized terms. Here are a few that I’ll be using in this post:

Noun: A word that refers to a person, a place, or a thing.  “Dog,” “teapot,” “man,” and “Dublin” are all nouns.

Adjective: A word that describes a noun or pronoun. “Ugly,” “funny,” “cold”, and “pretty” are all adjectives.

Case: A special form a noun or adjective can take that indicates its relationship to the other words around it.

How the genitive is used in Irish

The genitive case is used a lot in Irish. Three of the most common uses are:

• To show possession
• In a place where “of” would be used in English
• To turn a noun into an adjective.

Using the genitive to show possession

In English, if we want to say that something belongs to someone, we use an apostrophe followed by  the letter “s”:

Seán‘s house

The man‘s hat

If we’re talking about multiple owners, we use put the apostrophe after the letter “s”:

The Murphys’ boat

In Irish what we do instead is put the word that represents the owner(s) into the genitive case and put it AFTER the word for the thing that is owned: For example:

Seán = Seán and teach = house, but teach Sheáin = Seán’s house

Hata = hat and an fear = the man, but hata an fhir = the man’s hat

Ó Murchú = Murphy and bád = boat, but bád Uí Mhurchú = the Murphys’ boat

“Sheáin,” “an fhir,” and “Uí Mhurchú” are the genitive forms of “Seán,” “an fear,” and “Ó Murchú.”

In place of “of”

The genitive case is often used in Irish where we would use the word “of” in English. One of the easiest ways to show how this works is through Irish surnames.

You probably already know that the “Mac” (sometimes Anglicized to “Mc”) in an Irish surname means “son.” You may not know that the “Ó” (usually Anglicized to “O'”) means “grandson/descendent.”

All native Gaelic surnames originally meant “son/descendent of [a man’s given name, nickname, or occupation].” Instead of using a word for “of,” however, Irish puts the name, nickname, or occupation in the genitive case. For example:

Mac = Son.  Aodh = A man’s name.  Mac Aoidh = Son of Aodh: The Irish form of “McKay” or “McKee.”

Ó = Grandson/descendent.  Gabha = Blacksmith.  Ó Gabhann = Grandson/descendent of a Blacksmith: The Irish form of “Gowen” or “Going.”

When a noun becomes an adjective

We use nouns as adjectives (that is, as words that describe another noun) all the time in English. For example:

Butter knife

Fire extinguisher 

In the above examples, “butter” and “fire” are nouns acting as adjectives, because they describe what kind of “knife” or “extinguisher” we’re talking about.

In Irish, though, we can’t just put one noun in front of another as we do in English. What we do instead is take the first noun, put it in the genitive case, and then move it after the word it describes, which is where adjectives are placed in Irish:

Scian = knife.  Im = butter.  Scian ime = butter knife.

Múchtóir = extinguisher.  Dóiteán = fire.  Múchtóir dóiteáin = fire extinguisher.

“Ime” and “dóiteáin” are the genitive forms of “im,” and “dóiteán.”

Did you find this post helpful?

Did this post help you understand the importance of the genitive case in Irish grammar? Let us know by posting a comment below.

More like this in Aistear Reference Pack

If you like diving into Irish language grammar, and learning everyday Irish, you might enjoy our Aistear Reference Pack. It’s one of the courses available to Gaeilge Gach Lá Members. Its modules are:

1. Initial Mutations
2. Dealing with Dialects
3. A Guide to Numbers & Counting
4. A Guide to Nouns & Cases
5. Asking Questions in Irish
6. The Verb in Irish
7. Cracking the Copula

Each module is designed by experienced Irish language educators.

To access the Aistear Reference Pack, become a Gaeilge Gach Lá Member.