Learn Hardcore Icelandic: Penninn er þinn.

In Icelandic, the definite article is a suffix, not an independent word. You take the noun penni (“pen”) and add -inn to get penninn (“the pen”). If you want to say just “pen,” you drop the suffix and say penni.

Why do we still need þinn if penninn already means “the pen”?

The definite article (the suffix -inn) tells you the pen is specific, but it says nothing about ownership. þinn is the possessive pronoun (“your”). Icelandic marks definiteness and possession separately, so you need both the article on the noun and the possessive pronoun to express “your pen.”

How do I know that þinn is the correct form of “your” here?

Possessive pronouns in Icelandic agree in gender, number and case with the noun they refer to. Penni is a masculine noun in the nominative singular, so its matching form of “your” is þinn (masc. nom. sg.). If the noun were feminine, you’d use þín, and if it were neuter, þitt.

Why is þinn placed after er instead of immediately after penninn, like in penninn þinn?

Because Penninn er þinn uses þinn predicatively (“The pen is yours”). In that structure, the possessive pronoun stands alone after the verb er (“is”). If you want an attributive construction (“your pen”), you say penninn þinn (noun + article + possessive).

How do you pronounce the letter þ in þinn?

þ (thorn) is a voiceless “th,” like the th in English thin. So þinn sounds roughly like thin with a long “n” at the end: /θɪnː/.

Why does penni have two n letters?

The word penni belongs to a declension pattern where the stem itself ends in a geminated (doubled) consonant. That double n remains when you add the definite suffix, giving penninn.

If I want to say “The pen is mine” instead, what changes?

You swap out þinn (“your”) for minn (“my”). The rest stays the same: Penninn er minn = “The pen is mine.”