Hún kaus bláa kjólinn.

It breaks down like this:

• Hún = she
• kaus = chose
• bláa = blue, in a form that agrees with the noun
• kjólinn = the dress

So the sentence means She chose the blue dress.

Kaus is the past tense of the verb kjósa, which means to choose.

This verb is irregular, so you cannot predict kaus just by adding a regular past-tense ending. Some useful forms are:

• infinitive: kjósa
• present singular: kýs
• past singular: kaus
• past plural: kusu
• supine/past participle form used with auxiliaries: kosið

So Hún kaus = She chose.

In Icelandic, the definite article is usually attached to the end of the noun instead of standing as a separate word.

So:

• kjóll = dress
• kjólinn = the dress

That is very normal in Icelandic. English uses a separate word, but Icelandic usually uses a suffix.

Because this noun is the object of the verb, so it is in the accusative case.

For this word:

• nominative definite: kjóllinn = the dress as subject
• accusative definite: kjólinn = the dress as object

In this sentence, she is doing the choosing, and the dress is what is being chosen, so kjólinn is the correct form.

Compare:

• Kjóllinn er fallegur. = The dress is beautiful.
  Here it is the subject, so nominative kjóllinn.

• Hún kaus kjólinn. = She chose the dress.
  Here it is the object, so accusative kjólinn.

Because Icelandic adjectives have to agree with the noun in:

• gender
• number
• case
• definiteness

Here, kjólinn is:

• masculine
• singular
• accusative
• definite

So the adjective must match that, and the correct form is bláa.

That is why you get:

• bláa kjólinn = the blue dress

If the noun were indefinite, the adjective would be different.

Because definite noun phrases usually take the weak form of the adjective in Icelandic.

So:

• bláan kjól = a blue dress
  strong adjective form

• bláa kjólinn = the blue dress
  weak adjective form

This is a very important pattern in Icelandic:

• indefinite noun phrase -> usually strong adjective
• definite noun phrase -> usually weak adjective

So bláa is not just about case and gender; it also reflects the fact that the noun is definite.

It is in the accusative case.

The reason is that kjósa takes a direct object, and direct objects are often accusative in Icelandic. Here, the direct object is the blue dress, so the whole noun phrase is accusative:

• adjective: bláa
• noun: kjólinn

Both parts have to match the case of the noun phrase.

Yes. Kjóll is a masculine noun.

In Icelandic, grammatical gender does not have to match real-world gender or English expectations. A word for an object can be masculine, feminine, or neuter, and that is just part of its grammar.

So when learning nouns, it is best to learn the gender together with the word:

• kjóll = masculine noun

That matters because gender affects:

• adjective endings
• article forms
• pronouns and other agreement patterns

Yes. Hún kaus bláa kjólinn has the normal main-clause order:

• subject: Hún
• verb: kaus
• object: bláa kjólinn

So it follows the basic Subject-Verb-Object pattern that English speakers expect.

However, Icelandic also has a strong verb-second pattern, so other word orders are possible for emphasis or style. For example, you could move the object to the front, but the finite verb still tends to stay in second position.

The version given is the most neutral and straightforward one.

You would say:

Hún kaus bláan kjól.

The changes are important:

• kjólinn -> kjól because it is no longer definite
• bláa -> bláan because the adjective changes to the strong accusative masculine singular form

So the contrast is:

• Hún kaus bláa kjólinn. = She chose the blue dress.
• Hún kaus bláan kjól. = She chose a blue dress.

Yes. Kjósa can also mean elect or vote for, depending on context.

For example, with a person or political context, it could mean elect or vote for. But with dress, the natural meaning is simply choose.

So in this sentence, kaus is best understood as chose.