Bottnen är tunn.

Bottnen is the definite singular form of en botten.

• en botten = a bottom
• bottnen = the bottom

Depending on context, botten can mean the bottom of a container, the base of something, or even the seabed/floor. In this sentence, it simply means the bottom.

Because Swedish usually puts the definite article at the end of the noun instead of using a separate word in front.

So:

• botten = bottom
• bottnen = the bottom

That -en ending is doing the job that the does in English.

This is a spelling pattern in Swedish. Some nouns change slightly when endings are added.

With botten, the unstressed e in the middle drops in inflected forms:

• en botten
• bottnen
• bottnar

So bottnen is the correct definite form, not bottenen.

Är is the present tense of vara, which means to be.

So:

• är = is / are

In this sentence, är means is.

Because botten is an en-word: en botten.

When an adjective comes after är, it agrees with the gender and number of the noun:

• common gender singular (en-word) → tunn
• neuter singular (ett-word) → tunt
• plural → tunna

So:

• Bottnen är tunn. = correct

If the noun were an ett-word, you would use tunt instead.

Because tunn is being used predicatively here, after är.

In Swedish, adjectives after är usually show gender and number, but not the definite form used before nouns.

Compare:

• den tunna bottnen = the thin bottom

  • adjective before the noun
  • definite form: tunna

• bottnen är tunn = the bottom is thin

  • adjective after är
  • predicative form: tunn

So even though bottnen is definite, tunn is still correct here.

Yes, but it does not mean exactly the same thing grammatically.

• Bottnen är tunn. = The bottom is thin.
• Den tunna bottnen = the thin bottom

The first is a full sentence.
The second is a noun phrase, not a complete sentence by itself.

Not always. Tunn can be used in several ways, including:

• physically thin: en tunn vägg = a thin wall
• not thick/dense: tunt hår = thin hair
• diluted/watery: soppan är tunn = the soup is thin / watery

In Bottnen är tunn, the normal interpretation is physical thinness: the bottom is not thick.

Usually, bottnen is the natural choice if you mean the bottom of a specific thing.

• botten = bottom / a bottom
• bottnen = the bottom

So if you are talking about one particular object, Bottnen är tunn is the normal form.

Botten är tunn might appear in special contexts, but for a learner, bottnen is the safe and standard choice when you mean the bottom.

It follows a very common Swedish pattern:

subject + verb + adjective

So:

• Bottnen = subject
• är = verb
• tunn = adjective

This is directly parallel to English:

The bottom + is + thin