Kötturinn þvær sér.

Because -inn is the definite article attached to the end of the noun.

• köttur = cat
• kötturinn = the cat

Unlike English, Icelandic usually does not use a separate word like the. Instead, it often adds the article directly to the noun.

It is nominative singular.

That is the form used for the subject of the sentence, and here kötturinn is the one doing the action. The dictionary form is köttur, and the definite nominative singular form is kötturinn.

Köttur is a grammatically masculine noun.

That affects how the word is declined and how the definite article is added, but grammatical gender does not always match real-world sex in a strict way. So in a basic sentence like this, the important point is grammatical: köttur behaves like a masculine noun.

It comes from the verb að þvo, meaning to wash.

Þvær is the 3rd person singular present tense form, used with subjects like he, she, it, or a singular noun such as kötturinn.

This verb is a bit irregular:

• að þvo = to wash
• ég þvæ = I wash
• þú þværð = you wash
• hann/hún/það þvær = he/she/it washes

So the vowel changes from o in the infinitive to æ in the present tense forms.

Because Icelandic reflexive pronouns change form depending on case.

The main forms are:

• sig = accusative
• sér = dative
• sín = genitive

In this sentence, the reflexive is in the dative, so the correct form is sér.

For English speakers, this feels unusual because English uses just one form, such as himself, herself, or itself, without showing case this clearly.

Sér is the 3rd-person reflexive pronoun in the dative.

It refers back to the subject of the sentence. So here it points back to kötturinn.

A useful thing to remember is that sér is not tied to one English word. Depending on the context, it can mean:

• himself
• herself
• itself
• themselves

Here it means itself, because it refers back to the cat.

It can mean either one, depending on context.

The Icelandic present tense often covers both:

• a general present: The cat washes itself
• an action happening now: The cat is washing itself

If you want to make the ongoing action more explicit, Icelandic can use vera að + infinitive, for example:

• Kötturinn er að þvo sér = The cat is washing itself

A rough English-friendly approximation is:

KHOET-tur-inn thvair syehr

A few sound notes:

• k in Icelandic is often strongly aspirated, so it has a noticeable puff of air
• ö is not like English o; it is closer to German ö
• þ sounds like th in thing
• æ sounds roughly like eye
• é in sér has a yeh-like quality, so sér starts a bit like sy-

If you use IPA, a rough transcription is:

[ˈkʰœhtʏrɪn θvaiːr sjɛːr]

This sentence has a very straightforward order:

• Kötturinn = subject
• þvær = verb
• sér = reflexive object

So it looks quite similar to English.

However, Icelandic is a verb-second language in main clauses. That means the finite verb normally comes in the second position. In this sentence, the subject is first, so the verb naturally comes second.

For example, if you put another element first, the verb still stays second:

• Í dag þvær kötturinn sér. = Today the cat washes itself.

That verb-second pattern is an important feature of Icelandic sentence structure.