Við kveikjum upp í arninum.

Kveikjum is the 1st person plural present tense of kveikja.

So:

• að kveikja = to light / ignite / switch on
• við kveikjum = we light / we are lighting

In this sentence, við means we, so the verb has to match that subject.

In this sentence, kveikja upp works as a very common expression meaning to light a fire or get a fire going.

So upp is not random here. It adds the sense of starting up or kindling the fire. With a fireplace, stove, or fire, Icelandic very often uses kveikja upp.

That means learners should think of this as a useful chunk:

• kveikja upp = light up / kindle / start a fire

Because Icelandic often uses kveikja upp specifically when talking about making a fire in a fireplace, stove, or similar place.

If you leave out upp, the sentence may still be understandable, but kveikja upp í arninum sounds more natural for lighting a fire in the fireplace.

A helpful rough distinction is:

• kveikja ljós = turn on a light
• kveikja á kerti = light a candle
• kveikja upp í arninum = light a fire in the fireplace

So upp helps signal that this is about getting the fire going.

Because í can take either the dative or the accusative, depending on meaning.

Here the sentence describes location, not movement:

• in the fireplace = location

When í means in as a location, it takes the dative.

So:

• arinn = fireplace, hearth
• arninum = the fireplace in the dative singular

If the meaning involved motion into something, then accusative would be used instead.

In Icelandic, the definite article is usually attached to the noun as an ending, instead of being a separate word.

So:

• arinn = the fireplace / fireplace (dictionary form often appears with this ending in the nominative)
• arninum = the fireplace in the dative singular

English uses a separate word:

• in the fireplace

Icelandic often builds the into the noun itself.

The dictionary form is arinn.

That is the nominative singular form. In this sentence, it becomes arninum because:

1. the preposition í requires the dative here
2. the noun is definite: the fireplace

So you are seeing an inflected form, not the base form.

This is the normal Icelandic main-clause order:

• Við = subject
• kveikjum = finite verb
• then the rest of the sentence

Icelandic is a verb-second language in main clauses. That means the finite verb usually comes in the second position.

So this order is very natural:

• Við kveikjum upp í arninum.

You could move another element to the front for emphasis, but then the verb would still usually stay second.

Possibly, and people would likely understand you, but kveikja upp í arninum is the more natural expression when you mean lighting a fire in the fireplace.

Without upp, the sentence can feel less idiomatic in this context. For a learner, it is best to memorize:

• kveikja upp í arninum
• kveikja upp í ofninum
• kveikja upp

as common patterns for starting a fire.

No. Kveikja is a broad verb.

It can be used for things like:

• kveikja ljós = turn on a light
• kveikja á kerti = light a candle
• kveikja upp = light a fire

So the exact meaning depends on the object or the full expression around it.

That is why upp matters here: it helps narrow the meaning toward kindling a fire.

A rough learner-friendly pronunciation is something like:

• kveikjum ≈ KVAYK-yum

A few notes:

• kv is pronounced together at the start
• ei in Icelandic sounds roughly like ay in day
• kj before u often sounds somewhat like a ky sound to English speakers

This is only an approximation, but it may help you recognize the word when you hear it.

A rough approximation is:

• arninum ≈ AR-ni-num

The stress in Icelandic is normally on the first syllable, so:

• AR-ni-num

As always, exact pronunciation is better learned by listening, but the main thing is to stress the first syllable.

A very useful chunk is:

• að kveikja upp í + dative

For example:

• kveikja upp í arninum = light a fire in the fireplace
• kveikja upp í ofninum = light the stove / light a fire in the stove

This helps you remember two things at once:

1. kveikja upp is the natural expression for starting a fire
2. í takes the dative here because it describes location

So this sentence is a great example of a pattern, not just a one-off sentence.