Kvalitetskontrollen er grundig.

Because Norwegian usually writes compound nouns as one word, where English often uses two words.

So:

• kvalitet = quality
• kontroll = control / inspection

Together they become kvalitetskontroll = quality control.

This is very common in Norwegian. English speakers often want to separate words, but in Norwegian the combined form is normally correct.

The -s- is a linking element used in many Norwegian compounds.

So the structure is:

• kvalitet
  • -s-
    • kontroll
• kvalitetskontroll

It does not usually add meaning by itself. It mainly helps the compound sound natural and standard.

You will see this in many other words too, such as:

• arbeidsdag = workday
• livsglede = joy of life
• kvalitetsarbeid = quality work

So in this sentence, the -s- is just part of how the compound is formed.

The -en is the definite ending for many common-gender singular nouns in Norwegian.

So:

• en kvalitetskontroll = a quality control / a quality inspection
• kvalitetskontrollen = the quality control / the quality inspection

Norwegian often puts the at the end of the noun instead of using a separate word like English does.

Because Norwegian usually expresses definiteness by adding an ending to the noun.

Compare:

• English: the quality control
• Norwegian: kvalitetskontrollen

That final -en already means the, so no extra word is needed here.

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

So:

• jeg er = I am
• du er = you are
• den er = it is
• kvalitetskontrollen er = the quality control is

In this sentence, er links the subject kvalitetskontrollen with the description grundig.

Grundig is an adjective, and here it is used as a predicate adjective after er.

So the sentence structure is:

• Kvalitetskontrollen = subject
• er = verb
• grundig = adjective describing the subject

This is similar to English:

• The quality control is thorough.

Because predicate adjectives in Norwegian often change depending on gender and number.

Here, kvalitetskontrollen is:

• singular
• common gender

So the adjective stays in its basic form:

• Kvalitetskontrollen er grundig.

Compare:

• Et arbeid er grundig. = A piece of work is thorough.
  
  • Here arbeid is neuter, so the adjective still often looks the same in this case, but with many adjectives neuter can add -t.
• Kontrollene er grundige. = The inspections are thorough.
  
  • Plural gives grundige.

So grundig is the correct singular form here.

In Bokmål, this noun is normally treated as common gender, which means it takes en in the indefinite singular:

• en kvalitetskontroll

Then the definite singular becomes:

• kvalitetskontrollen

For many learners, it is easiest to think of this as the en-word pattern.

This is the normal word order for a simple statement in Norwegian:

• subject + verb + complement

So:

• Kvalitetskontrollen = subject
• er = verb
• grundig = complement/adjective

This is very similar to English:

• The quality control is thorough.

Norwegian does have special word order rules, especially the verb-second rule, but in a basic main clause like this, the sentence looks straightforward.

Usually, no—not if you mean the quality control in a normal, complete sentence.

• Kvalitetskontrollen er grundig. = The quality control is thorough.

If you remove -en, then kvalitetskontroll becomes indefinite and sounds more like quality control as a general concept. In that case, the sentence would usually need a different structure to sound natural.

So for this specific meaning, kvalitetskontrollen is the right form.

Yes, it is a natural and correct sentence in Norwegian.

It sounds like something you might say in a professional or technical context, for example about:

• manufacturing
• laboratory work
• auditing
• procedures
• product checks

It is a bit formal or workplace-oriented, but completely normal.

The plural would be:

• Kvalitetskontrollene er grundige.

Breakdown:

• kvalitetskontroller = quality controls / inspections
• kvalitetskontrollene = the quality controls / inspections
• grundige = thorough (plural form)

So singular vs. plural:

• Kvalitetskontrollen er grundig.
• Kvalitetskontrollene er grundige.

In long compound words, Norwegian usually keeps the main stress earlier in the word, often around the first main element of the compound. For learners, the most useful practical point is:

• do not try to stress every part equally
• say it as one unit
• let kontrollen flow naturally as the final part

The exact pronunciation can vary a little by speaker and dialect, but the important thing is to treat kvalitetskontrollen as one compound noun, not as separate English-style words.