Fingeravtrykket er tydelig.

Because fingeravtrykket is the definite singular form of the noun.

The basic noun is et fingeravtrykk = a fingerprint.
When Norwegian adds the meaning of the, it usually puts it on the end of the noun instead of using a separate word:

• et fingeravtrykk = a fingerprint
• fingeravtrykket = the fingerprint

The ending -et is the typical definite singular ending for many neuter nouns.

In Norwegian, the is often attached to the noun as a suffix.

So instead of saying something like the fingerprint, Norwegian usually says:

• fingeravtrykket

This is very normal. English uses a separate article, but Norwegian often builds definiteness into the noun itself.

A separate word like det is used in some other structures, especially when an adjective comes before the noun:

• det tydelige fingeravtrykket = the clear fingerprint

But in Fingeravtrykket er tydelig, the noun is already definite by itself, so no extra word is needed.

Yes. The noun is:

• et fingeravtrykk

That tells you it is neuter.

Some useful forms are:

• et fingeravtrykk = a fingerprint
• fingeravtrykket = the fingerprint
• fingeravtrykk = fingerprints or sometimes a fingerprint depending on context
• fingeravtrykkene = the fingerprints

As with many neuter nouns, the plural indefinite form is often the same as the singular indefinite form.

This is because tydelig is one of the adjectives that normally does not add -t in the neuter singular.

Many Norwegian adjectives do change in the neuter:

• en stor bil
• et stort hus

But adjectives ending in -ig often stay the same:

• en tydelig lyd
• et tydelig fingeravtrykk

So after er, it is still:

• Fingeravtrykket er tydelig

In the plural, though, it changes:

• Fingeravtrykkene er tydelige

Because tydelig in your sentence is a predicate adjective, not an adjective placed directly before the noun.

Compare these:

• det tydelige fingeravtrykket = the clear fingerprint
  Here the adjective comes before the noun, so you need the full definite noun phrase.

• Fingeravtrykket er tydelig = The fingerprint is clear
  Here the adjective comes after the verb er, so it describes the subject as a predicate.

This is a very important difference in Norwegian.

The sentence follows the normal pattern:

• subject + verb + adjective

So here you have:

• Fingeravtrykket = subject
• er = verb
• tydelig = predicate adjective

This is very similar to English:

• The fingerprint is clear

Norwegian main clauses also follow the verb-second rule, but in this simple sentence the subject comes first, so the word order looks straightforward.

Yes. Norwegian usually writes compounds as one word, so fingeravtrykk is correct.

It is made from:

• finger = finger
• avtrykk = print, impression, or mark

So literally it is something like finger-print.

This is very typical in Norwegian. English sometimes separates or hyphenates words where Norwegian prefers a single compound.

Yes. That would mean A fingerprint is clear or One fingerprint is clear, depending on context.

Compare:

• Et fingeravtrykk er tydelig. = A fingerprint is clear.
• Fingeravtrykket er tydelig. = The fingerprint is clear.

So the difference is mainly indefinite versus definite.

The plural would be:

• Fingeravtrykkene er tydelige. = The fingerprints are clear.

Notice two changes:

1. The noun becomes definite plural: fingeravtrykkene
2. The adjective becomes plural: tydelige

You could also say:

• Fingeravtrykk er tydelige. = Fingerprints are clear

That is the indefinite plural version.

To make it a question, put the verb first:

• Er fingeravtrykket tydelig? = Is the fingerprint clear?

To make it negative, add ikke after the verb:

• Fingeravtrykket er ikke tydelig. = The fingerprint is not clear.

This is a very common pattern in Norwegian:

• statement: Fingeravtrykket er tydelig.
• question: Er fingeravtrykket tydelig?
• negative: Fingeravtrykket er ikke tydelig.