Har du noensinne sett dette?

Because this is a yes/no question in Norwegian.

The statement would be:

Du har noensinne sett dette.
—but that is not a natural sentence because noensinne is usually used in questions, negatives, or other non-affirmative contexts.

A natural question is:

Har du noensinne sett dette?

Norwegian often forms yes/no questions by putting the finite verb first:

• Har du sett dette? = Have you seen this?
• Kan du komme? = Can you come?

So Har comes first because the speaker is asking a question.

Har sett is the present perfect.

It is made with:

• har = present tense of å ha (to have)
• sett = past participle of å se (to see)

So:

• å se = to see
• ser = see / sees
• så = saw
• sett = seen

In this sentence, har sett works like English have seen:

• Har du sett dette? = Have you seen this?

Noensinne means ever.

So:

• Har du noensinne sett dette? = Have you ever seen this?

It adds the idea of at any time in your life / at any point before now.

It is a slightly more formal or emphatic word than noen gang, which is also very common:

• Har du noen gang sett dette? = Have you ever seen this?

Both are correct. In everyday speech, many learners will hear noen gang more often.

Yes, but it can sound a bit more formal, literary, or emphatic than noen gang.

Compare:

• Har du noensinne sett dette? = Have you ever seen this?
• Har du noen gang sett dette? = Have you ever seen this?

For many everyday conversations, noen gang is the more common choice.
Noensinne is still perfectly natural, and native speakers definitely use it, but it may feel a little stronger or more polished depending on context.

That is a natural position for this adverb in a perfect-tense sentence.

The structure is:

• Har = auxiliary verb
• du = subject
• noensinne = adverb
• sett = past participle
• dette = object

So the sentence pattern is:

Har + subject + adverb + past participle + object

This is similar to English:

• Have you ever seen this?

You may also notice that adverbs often appear between the auxiliary and the main verb in Norwegian.

The base form is å se, meaning to see.

Important forms are:

• å se = to see
• ser = see / sees
• så = saw
• sett = seen

So in this sentence:

• Har du noensinne sett dette?
• literally: Have you ever seen this?

Because sett is the past participle, it is the form used with har.

Dette means this, while det usually means that / it.

So:

• dette = this
• det = that / it

Compare:

• Har du sett dette? = Have you seen this?
• Har du sett det? = Have you seen it / that?

A learner should know that Norwegian has forms related to distance, much like English:

• denne / dette / disse = this / these
• den / det / de = that / it / they / those, depending on context

Here, dette is used because the speaker means this thing.

Because dette is the neuter singular form of this.

Norwegian nouns have grammatical gender, and demonstratives agree with the noun.

Very roughly:

• denne = this, for many masculine/feminine singular nouns
• dette = this, for neuter singular nouns
• disse = these, plural

If the noun is not stated, Norwegian often uses dette by itself to mean this or this thing.

So Har du noensinne sett dette? is a natural standalone sentence meaning Have you ever seen this?

Yes. That is very common and natural.

• Har du sett dette? = Have you seen this?
• Har du noensinne sett dette? = Have you ever seen this?

Adding noensinne makes the question broader or more emphatic. It suggests something like:

• at any time before now
• in your life
• ever at all

So the version without noensinne is simpler and often enough in normal conversation.

This sentence is standard Bokmål and is also understandable to speakers generally.

In Nynorsk, you would more likely see:

Har du nokon gong sett dette?

or another close variant depending on style.

A few differences:

• Bokmål: du, noensinne / noen gang, dette
• Nynorsk: du, nokon gong, dette

So the given sentence is most naturally read as Bokmål.

Yes, very often.

Just like English ever, noensinne works well in questions and negatives.

Examples:

• Har du noensinne vært i Norge? = Have you ever been to Norway?
• Jeg har aldri noensinne sett noe lignende. = I have never ever seen anything like it.

In positive statements, noensinne is less common unless the sentence has a special meaning or emphasis. That is why learners most often meet it in:

• questions
• negative statements
• strong emphatic expressions

A very everyday version would often be:

Har du noen gang sett dette?

or simply:

Har du sett dette?

All three are possible:

• Har du noensinne sett dette? = slightly more formal/emphatic
• Har du noen gang sett dette? = very common everyday Have you ever seen this?
• Har du sett dette? = simple Have you seen this?

So if you want the most conversational version, noen gang is a very useful alternative to learn.

Pronunciation varies a bit by speaker and dialect, but in standard speech it is roughly:

NO-en-sin-ne

A learner should focus more on:

• keeping the stress near the beginning
• saying it smoothly as one word
• not trying to pronounce every letter too heavily

In fast speech, native pronunciation can sound more compressed than the spelling suggests. If you are a beginner, it is perfectly fine to learn the word first through listening and imitation rather than trying to map every sound exactly from the spelling alone.