Velkommen. Kom indenfor.

Because Kom is the imperative form of the verb at komme (to come).

In Danish, the imperative is used for commands, invitations, and instructions:

• Kom! = come!
• Sæt dig. = sit down.
• Se her. = look here.

So Kom indenfor means come in / come inside, and kommer would not fit here, because kommer means come/comes/is coming in a normal present-tense statement.

That is normal in Danish imperatives. Just like in English, the subject is usually understood rather than stated.

Compare:

• English: Come in.
• Danish: Kom indenfor.

The hidden subject is basically you, but it is normally left out. Danish can add a subject for emphasis in some cases, but the standard form is simply Kom indenfor.

Here it is normally written as one word: indenfor.

In Kom indenfor, indenfor means inside or in as an adverb, so the one-word spelling is the natural choice.

This is a common point of confusion because Danish also has inden for as two words in other contexts. For example, two-word forms can appear in expressions meaning things like within in a more literal or abstract sense.

So for this sentence:

• Kom indenfor = correct and natural

Here velkommen works like a fixed greeting or welcoming expression.

In other contexts, velkommen is an adjective:

• en velkommen gæst = a welcome guest

But in Velkommen., it functions more like a complete social phrase, similar to English Welcome.

So even though it comes from an adjective, in this sentence you can think of it as a standalone expression used when receiving someone.

Yes. In real speech and writing, Velkommen. works perfectly well as a complete utterance.

It is common in Danish to use short expressions like this on their own:

• Velkommen.
• Tak.
• Undskyld.
• Godmorgen.

They may not look like full sentences in a strict grammar sense, but they are complete and natural as spoken expressions.

You usually know from the situation, not from Kom itself.

The imperative form kom does not change for singular and plural in everyday use. So:

• to one person: Kom indenfor
• to several people: Kom indenfor

Context tells you whether the speaker is addressing one guest or multiple guests.

The same is true for many Danish commands.

It is neutral and very natural. It can be used in everyday situations when inviting someone into a home, office, or room.

It is not especially formal, but it is not rude or overly casual either. It is a standard polite invitation.

Some common alternatives are:

• Kom ind. = come in
• Bare kom indenfor. = just come in / please come in
• Værsgo at komme indenfor. = a more formal or extra-polite version

So Kom indenfor is a very useful default phrase.

They are very close in meaning.

• Kom ind = come in
• Kom indenfor = come inside / come in

Kom ind is a little shorter and very common. Kom indenfor can sound slightly warmer or more specifically like inviting someone into an indoor space, especially a home.

In many situations, either one would sound natural.

Because they express two separate speech acts:

1. Velkommen. = greeting the person
2. Kom indenfor. = inviting the person inside

Using two short sentences sounds clear and natural. In speech, there is often a small pause between them.

You could also see other punctuation in real life, such as:

• Velkommen! Kom indenfor!
• Velkommen, kom indenfor.

But the version with two short sentences is completely normal.

A rough English-friendly guide is:

• Velkommen ≈ VEL-kum-men

A few important notes:

• The first syllable vel- is stressed.
• The o in kommen does not sound like English oh.
• The final -en is usually a light, reduced ending.

A more careful learner-friendly approximation would be:

• VEL-kum-mən

Danish pronunciation varies by speaker and region, so it is best to learn this one by listening to native audio if possible.

A rough pronunciation guide is:

• Kom ≈ kum
• indenfor ≈ IN-nən-for

So the whole phrase is roughly:

• kum IN-nən-for

A few useful pronunciation notes:

• Kom is short and clipped.
• In fast speech, indenfor can sound smoother and more compressed than the spelling suggests.
• The stress is strongest on the first syllable of indenfor.

As with most Danish, the real spoken form is usually softer and less clearly pronounced than the spelling may suggest.

In regular grammar, yes, velkommen can behave like an adjective and change form depending on context:

• en velkommen gæst
• et velkomment afbræk
• velkomne gæster

But in the greeting Velkommen!, you should usually learn it as a fixed expression.

So for this sentence, you do not need to think about adjective agreement first. Just remember Velkommen as the normal welcoming phrase.