Learn Hardcore Norwegian: Den venstre døren er stengt.

døren = the door
When you add an adjective before a definite noun, Norwegian usually also adds den / det / de
So den venstre døren literally looks like the left the-door

This is the standard pattern in Bokmål:

døren = the door
den store døren = the big door
den venstre døren = the left door

English only uses one definite marker, but Norwegian often uses two in this kind of phrase.

Why is it den and not det?

Because dør is a common-gender noun in Norwegian.

Its basic form is:

en dør = a door

Common-gender nouns use den in phrases like this:

den venstre døren

If it were a neuter noun, you would use det instead:

et hus = a house
det store huset = the big house

So the choice of den comes from the gender of dør.

Why is the adjective venstre written that way?

In definite noun phrases, adjectives often appear in an -e form:

den store døren
den gamle bilen

With venstre, the form is already venstre, so it stays the same:

den venstre døren

Also, venstre is commonly used as a side/direction adjective, and it does not take any extra ending here.

What exactly is stengt here? Is it a verb or an adjective?

It comes from the verb å stenge = to close / to shut, but here it is being used like an adjective.

So:

er = is
stengt = closed / shut

Together, er stengt means is closed.

This is very common in Norwegian. A past participle is often used after er to describe a state:

Døren er stengt = The door is closed
Butikken er stengt = The shop is closed

So in this sentence, stengt describes the condition of the door.

Does stengt mean the door is locked?

Not necessarily.

stengt means closed or shut. A door can be stengt without being locked.

If you specifically want to say locked, Norwegian usually uses:

låst = locked

So:

Døren er stengt = The door is closed
Døren er låst = The door is locked

Sometimes a closed door may also be locked in real life, but the word stengt itself does not mean that.

Why is er used here?

Er is the present tense of å være = to be.

The sentence has a very simple structure:

Den venstre døren = the subject
er = the verb
stengt = the description

So the whole sentence follows the pattern:

subject + verb + description

That is the same basic idea as in English:

The left door is closed

Can I say døra instead of døren?

Yes. In Bokmål, both are possible.

You may see:

døren
døra

Both mean the door.

In general:

døren can sound more neutral or formal
døra can sound more colloquial or more clearly feminine

So these are both possible:

Den venstre døren er stengt
Den venstre døra er stengt

Could I also say Døren til venstre er stengt?

Yes, absolutely.

That means roughly:

The door on the left is closed

This version is often very natural when you are identifying something by location.

There is a small difference in feel:

den venstre døren = the left door
døren til venstre = the door on the left

Both are correct. Depending on context, some speakers may find døren til venstre a little more natural in everyday speech.

Why is the word order Den venstre døren er stengt?

Because this is a normal Norwegian main clause.

The order is:

Den venstre døren = subject
er = finite verb
stengt = complement/predicate

Norwegian main clauses usually follow the verb-second rule, often called V2. That means the finite verb usually comes in the second position.

Here, the subject comes first, so er comes second:

Den venstre døren er stengt

That is the standard word order for a simple statement like this.