Hitinn er mikill í dag, svo ég drekk meira vatn.

Hiti means heat or temperature in an indefinite sense, while hitinn means the heat or the temperature.

Icelandic usually puts the definite article at the end of the noun as a suffix, instead of using a separate word like English the.

• hiti = heat
• hitinn = the heat

In this sentence, hitinn is the subject.

Because mikill has to agree with hitinn in gender, number, and case.

Here, hitinn is:

• masculine
• singular
• nominative

So the adjective also appears in the masculine singular nominative form:

• mikill = masculine singular nominative

The other forms would be used in different grammatical situations:

• mikli is a weak form, often used before certain definite nouns in attributive position
• mikið is neuter singular

That is because mikill is a predicate adjective here, not an attributive adjective.

In other words:

• hitinn er mikill = the heat is great/high

The adjective comes after er and describes the subject through the verb to be. In Icelandic, predicate adjectives normally use the strong form, even when the noun is definite.

Compare:

• mikill hiti = great heat / a lot of heat
• hitinn er mikill = the heat is great / high

English often uses a dummy subject like it in weather and general condition sentences, but Icelandic does not always do the same.

This sentence uses a real subject:

• Hitinn er mikill = the heat is high/great

That is perfectly natural in Icelandic.

You can also say:

• Það er heitt í dag = it is hot today

So Icelandic can express this idea in more than one way. The version with hitinn focuses more on the heat or the temperature itself.

Í dag is a very common fixed expression meaning today.

Here:

• í = in
• dag = accusative singular of dagur (day)

Even though it literally looks like in day, you should learn í dag as a set phrase meaning today.

That is a very common learner question, because í can take either accusative or dative depending on meaning.

In this expression, í dag, Icelandic uses the accusative. It is best to treat í dag as a fixed time expression.

So:

• í dag = today
• not í degi

This is one of those phrases that is easiest to memorize as a whole.

Here svo means so, therefore, or as a result.

It connects the two clauses:

• Hitinn er mikill í dag = the heat is high today
• svo ég drekk meira vatn = so I drink more water

Be aware that svo can have several meanings in Icelandic depending on context, including so, then, and sometimes and then.

Because drekk is the present-tense form for ég.

The verb is drekka = to drink.

Present tense:

• ég drekk = I drink
• þú drekkur = you drink
• hann/hún/það drekkur = he/she/it drinks

So with ég, you need drekk.

Because meira agrees with vatn, and vatn is neuter singular.

Meira is the comparative form meaning more. It comes from the same adjective family as mikill.

Here the forms are:

• mikill = much/great, masculine
• meiri = more, masculine/feminine
• meira = more, neuter

Since vatn is a neuter noun, Icelandic uses:

• meira vatn = more water

Yes. They belong to the same adjective/comparison pattern.

Think of it like this:

• mikill = much / great / large amount
• meira = more
• mest = most

So the sentence uses:

• mikill for the heat is high/great
• meira for more water

Even though the English translations may vary, the Icelandic forms are related.

Vatn is the direct object of drekk, so it is in the accusative case.

However, for this noun, the nominative and accusative singular look the same:

• nominative: vatn
• accusative: vatn

So you do not see a visible ending change here, but grammatically it is accusative.

Because vatn is indefinite here.

The sentence means that the speaker drinks more water in general, not the water in some specific, already known sense.

Also, water is a mass noun, so Icelandic often leaves it indefinite in this kind of statement:

• ég drekk vatn = I drink water
• ég drekk meira vatn = I drink more water

Yes, to some extent.

For example, you could also say:

• Í dag er hitinn mikill, svo ég drekk meira vatn.

That is also natural. Icelandic often allows different elements to come first for emphasis, but the language still follows important word-order rules, especially the verb-second pattern in main clauses.

So both of these are fine:

• Hitinn er mikill í dag
• Í dag er hitinn mikill

The difference is mostly one of emphasis and style.

A rough learner-friendly approximation is MIH-kitl.

A few useful points:

• stress is on the first syllable: MI-
• Icelandic ll is often not pronounced like normal English l
• in words like mikill, it often sounds like a tl-type sound

So if you say something close to MIH-kitl, you will be much closer than if you pronounce it like plain English mill.