Jörðin er blaut.

Because -in is the definite article attached to the noun.

• jörð = earth / ground
• jörðin = the earth / the ground

Icelandic often puts the at the end of the noun instead of using a separate word the way English does.

The dictionary form is jörð.

That is the indefinite singular form, and it is a feminine noun. In this sentence, the form jörðin is nominative singular definite: the earth / the ground.

Jörð is feminine.

That matters because adjectives in Icelandic must agree with the noun they describe. Since jörðin is feminine singular, the adjective also has to be in the feminine singular form.

That is why the sentence has blaut.

Because the adjective has to agree with jörðin.

For blautur meaning wet, the singular nominative forms are:

• blautur = masculine
• blaut = feminine
• blautt = neuter

Since jörðin is feminine singular, the correct form is blaut.

So:

• vegurinn er blautur = the road is wet
• jörðin er blaut = the ground is wet
• gólfið er blautt = the floor is wet

Er is a form of vera, the Icelandic verb to be.

In this sentence, er means is.

So the structure is:

• Jörðin = the ground / the earth
• er = is
• blaut = wet

It is in the nominative case.

That is because jörðin is the subject of the sentence. In a simple sentence like X er Y (X is Y), the subject is normally nominative, and the adjective also matches it.

So both the noun and the adjective are functioning in the basic subject pattern here.

Because blaut is a predicate adjective here. It comes after er and tells you what the subject is like.

This is similar to English:

• The ground is wet.

If you want the adjective directly before the noun, as in the wet ground, Icelandic uses a different structure, and the adjective changes form:

• blauta jörðin = the wet ground

So:

• Jörðin er blaut. = The ground is wet.
• Blauta jörðin = the wet ground

Yes. Jörð can mean several related things, depending on context, such as:

• earth
• ground
• soil
• sometimes land

In everyday context, Jörðin er blaut will often be understood as the ground is wet. In another context, it could refer to the Earth.

A rough English-friendly guide is:

• Jörðin ≈ YER-thin or YUR-thin
• er ≈ ehr
• blaut ≈ bloyt

A few helpful notes:

• j in Icelandic sounds like English y in yes
• ö does not have an exact English equivalent; it is a rounded front vowel
• ð is like th; in jörðin it is voiced, like th in this
• au in Icelandic is not like English ow in out; it is more like oy with lip-rounding

Also, Icelandic stress is usually on the first syllable of each word:

• JÖR-ðin
• ER
• BLAUT

In this sentence, it is capitalized because it is the first word of the sentence.

If the same word appeared in the middle of a sentence, it would normally be written jörðin unless there were some special reason to capitalize it.