Hitinn er núll.

Hiti is the basic noun, meaning temperature, heat, or sometimes fever depending on context.

Hitinn is the definite form, so it means the temperature. Icelandic usually adds the definite article to the end of the noun instead of using a separate word like English the.

So:

• hiti = temperature
• hitinn = the temperature

In this sentence, Icelandic is talking about a specific temperature, so hitinn is the natural choice.

Er is the present-tense form of the verb vera (to be).

So here it works exactly like English is:

• hitinn = the temperature
• er = is
• núll = zero

Because hitinn is singular, you use er, not a plural form.

In Icelandic, the definite article is usually attached to the noun as an ending.

That means English:

• the temperature

becomes Icelandic:

• hitinn

This is very common in Icelandic. A learner often expects a separate word, but Icelandic normally builds the right into the noun.

Because the unit is understood from context.

Just like in English, if everyone already knows you are talking about temperature, you can simply say zero. Icelandic can do the same.

So Hitinn er núll. means The temperature is zero.

If you want to be more explicit, you can add a unit, for example gráður (degrees) when appropriate.

Yes, it is grammatical and understandable.

It sounds like a straightforward statement about a measured temperature: The temperature is zero.

For everyday weather talk, though, Icelandic speakers often use other expressions too, such as:

• Það eru núll gráður. = It is zero degrees.
• Það er frost. = It is freezing / there is frost.

So Hitinn er núll. is correct, but in casual weather conversation another phrasing may be more common.

Hiti can mean several related things:

• temperature
• heat
• warmth
• sometimes fever

Context tells you which meaning is intended.

In Hitinn er núll., the meaning is clearly temperature, not fever or heat in a general sense.

A rough guide is:

HI-tin er NOO-tl

A few helpful notes:

• hi- has an Icelandic i sound, not exactly like English.
• er is like ehr.
• ú in núll is like oo in food.
• ll in Icelandic is often pronounced with a special sound that English speakers often approximate as tl.

So núll may sound a bit like nootl.

Hitinn is in the nominative singular because it is the subject of the sentence.

This is the basic subject form:

• hitinn = the temperature

After er, núll functions as the complement: it tells you what the temperature is.

Because Icelandic does not need a dummy subject here.

English often says things like It is zero degrees, but this Icelandic sentence is structured more like:

The temperature is zero.

So the real subject is already there: hitinn. Nothing extra is needed.

You move the verb to the front:

Er hitinn núll?

That means Is the temperature zero?

This is very common in Icelandic yes/no questions: the verb comes first.