Ingen må true barnet.

Ingen means no one / nobody in this sentence.

It is standing on its own as a pronoun:

• Ingen må true barnet. = No one must/should threaten the child.

You can also use ingen before a noun, where it means no / not any:

• ingen biler = no cars
• ingen problemer = no problems

So here, ingen is the subject of the sentence.

Because after a modal verb like må, Norwegian normally uses the infinitive without å.

So:

• må true
• kan true
• skal true
• vil true

Not:

• må å true

This is similar to English, where you say must threaten, not must to threaten.

Må usually means must or have to.

But in a sentence like Ingen må true barnet, the overall meaning is usually closer to:

• No one is allowed to threaten the child
• Nobody must threaten the child
• Nobody should threaten the child

So the sentence expresses a prohibition or strong rule.

A useful thing to know is that in everyday Norwegian, people often use får ikke to make this kind of meaning very clear:

• Ingen får true barnet. = No one may / is allowed to threaten the child.

But Ingen må true barnet is still understandable and grammatical.

True is the infinitive form of the verb, meaning to threaten.

So the parts are:

• må = modal verb
• true = infinitive main verb

Other forms of true include:

• å true = to threaten
• truer = threatens / am threatening / are threatening
• truet = threatened

Example:

• Han truer barnet. = He threatens the child.

Because barnet is the definite form and means the child.

The noun is:

• et barn = a child
• barnet = the child

So:

• Ingen må true barn. = No one must threaten children / child(ren) in general
• Ingen må true barnet. = No one must threaten the child

Since the English meaning already uses the child, barnet is the right form.

Because barn is a neuter noun.

For many neuter nouns in Norwegian:

• indefinite singular: et barn
• definite singular: barnet

That -et ending marks the.

Compare:

• et hus → huset = the house
• et eple → eplet = the apple
• et barn → barnet = the child

The word order is:

• Ingen = subject
• må = finite verb
• true = infinitive
• barnet = object

So:

Ingen | må | true | barnet

This is a normal main-clause pattern in Norwegian.

Also, Norwegian usually follows the V2 rule in main clauses, which means the finite verb comes in the second position. Here the subject is first, so må comes second.

Grammatically, ingen is usually treated as singular when it means no one.

So you would normally continue with singular agreement if needed.

Example:

• Ingen vet det. = No one knows it.

But in meaning, it refers to the absence of any people at all, so in English it may feel similar to nobody.

In theory, må can relate to necessity, so a very literal reading could sound like no one has to threaten the child. But that is usually not how this sentence is understood.

In normal usage, Ingen må true barnet is understood as a prohibition:

• Nobody must
• Nobody is allowed to
• No one should

If you want to say No one has to threaten the child, that would be an unusual idea anyway, and Norwegian would normally express that more clearly in another way.

Yes, it is grammatical and understandable.

However, many speakers might prefer a clearer prohibition with får ikke:

• Ingen får true barnet. = No one is allowed to threaten the child

That can sound more natural in everyday speech if the idea is about permission or prohibition.

Still, Ingen må true barnet is perfectly possible and easy to understand.

Then you would use the indefinite form:

• Ingen må true et barn. = No one must threaten a child

Compare:

• et barn = a child
• barnet = the child

So the difference is the same basic idea as in English: indefinite vs. definite.