Hún hvíslar að systur sinni í bókasafninu.

Hvíslar is the 3rd person singular present tense form of the verb að hvísla.

Because the subject is hún = she, Icelandic uses:

• ég hvísla = I whisper
• þú hvíslar = you whisper
• hún hvíslar = she whispers

So hún hvíslar means she whispers.

With the verb að hvísla, Icelandic often uses að before the person being whispered to.

So:

• hvísla að einhverjum = whisper to someone

Here, að systur sinni means to her sister.

This is something you largely have to learn with the verb: Icelandic verbs often choose a specific preposition, and that preposition then controls a certain case.

Because að here takes the dative case, and systir changes form in the dative singular.

The noun looks like this:

• nominative: systir = sister
• dative: systur = to a sister / to the sister

Since the phrase is að systur sinni, the noun must be in the dative, so systir becomes systur.

Sinni is a reflexive possessive form. It means that the sister belongs to the subject of the sentence.

So systur sinni means her own sister.

In this sentence, the subject is hún, so sinni tells you that she is whispering to her own sister, not someone else’s sister.

This is a very important distinction in Icelandic:

• systur sinni = to her own sister
• systur hennar = to her sister, but not necessarily her own; it could refer to another woman’s sister

Sinni is the dative singular feminine form of the reflexive possessive sinn.

It agrees with the noun it describes, not with the subject directly. Since systur is:

• feminine
• singular
• dative

the possessive must match it, so you get sinni.

That is why the phrase is:

• að systur sinni

and not some other form such as sinn or sína.

Because í can take different cases depending on meaning.

Here it means in the library as a location, so it takes the dative.

• í bókasafni = in a library
• í bókasafninu = in the library

If there were movement into the library, Icelandic would normally use the accusative instead.

So the sentence uses í bókasafninu because it describes where the whispering happens, not movement.

The ending -inu shows two things at once:

• the noun is definite = the library
• the noun is in the dative singular

The base noun is bókasafn = library.

Then:

• bókasafn = a library
• bókasafnið = the library
• í bókasafninu = in the library

Icelandic usually adds the as an ending on the noun rather than using a separate word like English does.

Yes, Icelandic word order is fairly flexible, but it still follows important patterns, especially the verb-second rule in main clauses.

The neutral order here is:

• Hún hvíslar að systur sinni í bókasafninu.

But you could also move the location to the front for emphasis:

• Í bókasafninu hvíslar hún að systur sinni.

That still works because the finite verb hvíslar stays in the second position.

So the order can change, but not completely freely.

A rough guide is:

• Hún ≈ hoon
• hvíslar ≈ HVEE-slar
• að ≈ ath
• systur ≈ SIS-tur
• sinni ≈ SIN-nih
• í bókasafninu ≈ ee BO-ka-saf-ni-nu

A few useful points:

• í is like ee
• á/í/ú vowels are usually long when stressed
• ð in að is like the th in this, though in some positions it can be very weak
• hv in modern Icelandic is often pronounced close to kv by many speakers

A more Icelandic-sounding pronunciation will depend on dialect and speaking speed, but this rough version is enough to get started.

Not in natural English. Even though að can sometimes mean at or to, with this verb the whole phrase is best understood as to her sister.

So it is better to learn it as a pattern:

• hvísla að einhverjum = whisper to someone

This is a good example of why translating Icelandic prepositions word-for-word is not always helpful. The important thing is how the verb and preposition work together.