Settu spurningarmerkið í lok setningarinnar.

Settu is the singular imperative of the verb setja, which means to put, to place, or to set.

So in this sentence, settu means put! or place! when speaking to one person.

A very common pattern in Icelandic commands is:

• Settu ... = Put ...
• Lestu ... = Read ...
• Skrifaðu ... = Write ...

In Icelandic, just like in English commands, the subject you is usually understood and not stated.

So:

• Settu spurningarmerkið ... = Put the question mark ...
• understood subject = you

If you really wanted to make the subject explicit, you could add þú, but in a normal instruction it is usually omitted.

Icelandic often makes compound nouns where English uses two separate words.

So spurningarmerki means question mark and is built from:

• spurning = question
• merki = mark / sign

The first part appears as spurningar-, which is a very common way to build compounds in Icelandic.

So literally it is something like:

• spurningarmerki = question-sign

That is completely normal in Icelandic.

The ending -ið is the definite article, meaning the.

So:

• spurningarmerki = a question mark
• spurningarmerkið = the question mark

In Icelandic, the is very often attached to the end of the noun instead of being a separate word.

Here, spurningarmerkið is the direct object of the verb settu, so it is in the accusative case.

The noun spurningarmerki is neuter, and for many neuter nouns the nominative and accusative singular look the same. So the form does not change visibly here apart from the definite ending.

That means:

• spurningarmerkið can be both the question mark as subject and the question mark as object, depending on the sentence

In this sentence, it is the object because it is the thing you are being told to put.

Í lok is a fixed expression meaning at the end or in the end part of something.

So:

• í lok setningarinnar = at the end of the sentence

You should not expect Icelandic prepositions to match English ones word-for-word. English uses at the end of, while Icelandic uses í lok + a following noun in the genitive.

So it is best to learn í lok as a set phrase.

Setningarinnar is the genitive singular definite form of setning, which means sentence.

Breakdown:

• setning = sentence
• setningar = of a sentence
• setningarinnar = of the sentence

It is in the genitive because í lok is followed by the thing whose end you mean:

• í lok bókarinnar = at the end of the book
• í lok dagsins = at the end of the day
• í lok setningarinnar = at the end of the sentence

So setningarinnar means of the sentence.

Because this is a command.

In Icelandic, imperative sentences normally begin with the imperative verb:

• Settu ... = Put ...
• Lokaðu ... = Close ...
• Skrifaðu ... = Write ...

That is very similar to English, where commands also often begin with the verb:

• Put the question mark at the end of the sentence.

So the word order here is very natural.

If you are giving the command to more than one person, you would normally use the plural imperative:

• Setjið spurningarmerkið í lok setningarinnar.

So the difference is:

• settu = command to one person
• setjið = command to more than one person

The rest of the sentence stays the same.