Den overlevende er trygg.

Here, den works a bit like the.

In Norwegian, when an adjective or adjective-like form stands by itself and refers to a person or thing, you often use den, det, or de in front of it. So:

den overlevende = the survivor / the surviving one

This is very common with words that describe a person by a quality or condition, such as:

den skadde = the injured person
de rike = the rich

So den is not random here; it helps turn overlevende into a definite noun phrase.

Overlevende comes from the verb å overleve = to survive.

It is originally a participle-like form, similar to surviving in English, but in Norwegian it is also very commonly used like a noun:

en overlevende = a survivor
den overlevende = the survivor

So in this sentence, overlevende is functioning as a noun meaning survivor, even though its form is closely connected to the verb å overleve.

Because words like overlevende often keep the same basic form and use den/de to show definiteness.

Compare:

en overlevende = a survivor
den overlevende = the survivor
de overlevende = the survivors

This is normal for many -ende words used this way. You can think of den as carrying the definite meaning here.

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

So:

er = is / are

In this sentence, it links the subject den overlevende to the description trygg.

Very common forms of å være are:

er = am/is/are
var = was/were
har vært = have/has been

Because predicate adjectives in Norwegian agree mainly with number and, in singular, sometimes with gender.

Here, the subject is a singular person, so the basic form trygg is used:

Den overlevende er trygg.

Compare:

Barnet er trygt. = The child is safe.
Here trygt is used because barnet is neuter singular.

De overlevende er trygge. = The survivors are safe.
Here trygge is used because the subject is plural.

A very important point: after er, adjectives do not become -e just because the subject is definite. So:

den trygge mannen = the safe / confident man
but
mannen er trygg = the man is safe / confident

In this sentence, it is best understood as the.

On its own, den can sometimes mean that, especially when it is stressed or contrasted. But in a phrase like den overlevende, it is normally just the standard definite form used before an adjective-like word functioning as a noun.

So a learner should usually read:

den overlevende = the survivor

not that survivor, unless the context clearly emphasizes that meaning.

Yes.

Overlevende itself does not tell you whether the survivor is male or female. It is gender-neutral in meaning, just like English survivor.

If context makes it clear, it can refer to either:

Den overlevende er trygg. = The survivor is safe.

If you want to be more specific, you would add another noun, for example:

den overlevende mannen = the male survivor / the surviving man
den overlevende kvinnen = the female survivor / the surviving woman

This is the normal Norwegian main-clause order:

subject + verb + complement

So:

Den overlevende + er + trygg

This is the most natural neutral order for a statement.

Norwegian main clauses also follow the verb-second rule, so if you put something else first, the verb still comes second:

Nå er den overlevende trygg. = Now the survivor is safe.

A different order like Trygg er den overlevende is possible only in very marked, poetic, or highly emphatic language. It is not the normal everyday version.

Here are some useful patterns:

En overlevende er trygg. = A survivor is safe.
Den overlevende er trygg. = The survivor is safe.
Overlevende er trygge. = Survivors are safe.
De overlevende er trygge. = The survivors are safe.

This shows two helpful things:

1. overlevende stays the same in many forms
2. trygg changes to trygge in the plural