The Genitive Case and Possession

The genitive case is also sometimes called the possessive case, and for good reason: it is integral in indicating the possessor (somebody or something that possesses something. I love it when the grammar terminology is clear and easily understood). 

The genitive case It is equivalent to the English:

• apostrophe + s (like the government’s failures or man’s folly), or
• the preposition of (like the failures of the government or the folly of man).

Here, we’re not going to go into how to form the genitive case, just how to use it to indicate possession. If you’d like to learn how to form the genitive of a noun, I recommend Brian Casper’s YouTube channel Icelandic For Foreigners, starting with this video .

Note also that here we’re talking about the genitive case for nouns, not pronouns. You can also indicate possession in Icelandic with various types of pronouns, notably:

• the possessive pronouns minn and þinn, 
• the personal pronouns in the genitive case, and with
• the reflexive possessive pronoun sinn.
  

What most people get wrong about using a genitive noun is that they think it works just like the genitive pronouns, but that’s not the case. Most notably, the difference is in how we use the definite article (the word the in English).

The Definite Article 

You never, ever, ever* use the definite article (the word the in English) with the possession before a genitive noun. When the possessor is a pronoun, sure, but not with genitive nouns.

• Bíll nýja gaursins er miklu flottari en minn > The new guy’s car is way nicer than mine.
• Hugmyndafræði skólans samræmist ekki nýjustu tísku > The school’s ideology doesn’t conform with the latest fashion.
• Móðir nemandans kom og kvartaði > The student’s mother came and complained.
• Þú hefur hjarta ljóns en heila lindýrs > You have the heart of a lion but the brain of a mollusc.
  

*I mean, it’s language. Never say never. But it’s still a pretty good rule.

By the by, notice the word order: it’s not the student’s mother, it’s mother the student’s. This works exactly like when the possessor is a pronoun, so it’s standard practice in Icelandic.