Ég samþykki ekki þessa ákvörðun.

Because ákvörðun is a feminine noun in the accusative singular, and the demonstrative þessi has to match it in gender, number, and case.

Here, þessa ákvörðun means this decision as the direct object of the verb.

A quick comparison:

• þessi ákvörðun = this decision (nominative, subject form)
• þessa ákvörðun = this decision (accusative, object form)

Since Ég samþykki ... takes a direct object, Icelandic uses the accusative here.

It is in the accusative singular.

The verb samþykkja normally takes a direct object, and direct objects in Icelandic are often in the accusative. In this sentence, þessa ákvörðun is the thing being accepted or not accepted, so it appears in the accusative.

You can think of it like this:

• Ég samþykki ákvörðunina. = I accept the decision.
• Ég samþykki ekki þessa ákvörðun. = I do not accept this decision.

Here it is a verb: the 1st person singular present tense of samþykkja.

So:

• ég samþykki = I accept / I approve

This can be confusing because samþykki can also be a noun meaning consent or approval in other contexts. But in this sentence, it is clearly the verb because it follows the subject Ég.

The infinitive is samþykkja, meaning to accept, to approve, or sometimes to agree to depending on context.

A few forms:

• að samþykkja = to accept
• ég samþykki = I accept
• þú samþykkir = you accept
• hann/hún samþykkir = he/she accepts

In Icelandic, ekki usually comes after the finite verb in a normal main clause.

So the pattern here is:

• Ég = subject
• samþykki = finite verb
• ekki = not
• þessa ákvörðun = object

That makes Ég samþykki ekki þessa ákvörðun the natural word order.

This is very common in Icelandic:

• Ég veit ekki. = I do not know.
• Hún kemur ekki. = She is not coming.

No, that would not be normal Icelandic.

In a standard main clause, the finite verb usually comes early, and ekki follows it. So:

• correct: Ég samþykki ekki þessa ákvörðun.
• not normal: Ég ekki samþykki þessa ákvörðun.

Icelandic word order is often described as verb-second in main clauses, meaning the finite verb tends to come in the second position.

Ákvörðun is feminine.

That is why the demonstrative has the feminine form þessa here.

You can often see the gender from dictionary entries, where it may be marked as:

• ákvörðun (kvk.)

Here kvk. means feminine.

Some Icelandic nouns have the same form in more than one case, or only a small visible difference depending on whether they take an article or adjective/demonstrative.

With ákvörðun, the case is especially clear because of the word before it:

• þessi ákvörðun = nominative
• þessa ákvörðun = accusative

So even if the noun itself does not change dramatically here, the whole noun phrase shows the case.

A rough English-friendly guide:

• þessa ≈ THESS-a
• ákvörðun ≈ OWK-vur-thun or OWK-vor-thun

A few important pronunciation notes:

• þ is like th in thing
• ð is like th in this, though in some positions it can sound weaker
• ö is a rounded vowel that does not exist exactly in English, so learners often approximate it at first

And Ég samþykki ekki þessa ákvörðun as a whole is roughly:

• Yehg soum-thik-kih ehk-kih THESS-a OWK-vor-thun

This is only approximate, but it can help as a starting point.

It can overlap with all three, depending on context.

In this sentence, accept is usually the safest translation:

• Ég samþykki ekki þessa ákvörðun. = I do not accept this decision.

But in other contexts it can mean:

• approve
• consent to
• agree to

For example, in formal or political language, it may sound like approve. In personal or legal contexts, it may sound more like consent to.

Yes, but the meaning changes slightly.

• þessa ákvörðun = this decision
• ákvörðunina = the decision

So:

• Ég samþykki ekki þessa ákvörðun. = I do not accept this decision.
• Ég samþykki ekki ákvörðunina. = I do not accept the decision.

The first points to a specific decision in a more immediate or contrastive way.

It is perfectly normal Icelandic and can work in both formal and neutral contexts.

It sounds especially natural in:

• discussions
• meetings
• official statements
• arguments
• written complaints

In casual speech, Icelanders might also say something simpler depending on context, but this sentence itself is completely natural.

You would change the verb to the past tense:

• Ég samþykkti þessa ákvörðun.

That means I accepted this decision.

Compare:

• Ég samþykki þessa ákvörðun. = I accept this decision.
• Ég samþykkti þessa ákvörðun. = I accepted this decision.
• Ég samþykki ekki þessa ákvörðun. = I do not accept this decision.

Yes, in many contexts it can.

Even if the shown meaning is I do not accept this decision, the Icelandic sentence may also be understood as:

• I do not approve of this decision

especially in formal, political, or administrative contexts.

So the exact English wording depends on the situation, even though the Icelandic structure stays the same.