Learn Hardcore Icelandic: Augun hennar verða stór þegar hún sér uppáhalds leikfangið sitt aftur. - Her eyes become big when she sees her favorite toy again.

Augun – the eyes (neuter plural nominative, definite)
hennar – her (non‑reflexive possessive pronoun, genitive)
verða – become / get (3rd person plural present of að verða)
stór – big / large / wide (adjective, neuter plural nominative in predicative position)
þegar – when (subordinating conjunction)
hún – she (3rd person singular feminine, nominative)
sér – sees (3rd person singular present of að sjá)
uppáhalds – favorite (indeclinable adjective)
leikfangið – the toy (neuter singular accusative, definite)
sitt – her (own) (reflexive possessive pronoun, neuter singular accusative)
aftur – again

So a very literal rendering is:
“The eyes her become big when she sees favorite the toy her-own again.”

Why is it “Augun hennar” and not “hennar augu” like English “her eyes”?

In Icelandic, possessive pronouns (like hennar, minn, þinn) most often come after the noun:

Augun hennar – her eyes
Húsið mitt – my house
Bíllinn þinn – your car

You can put the possessive in front (hennar augu), but that is:

much less common in everyday speech
often more emphatic or stylistic

So Augun hennar is the normal, neutral way to say “her eyes.”

Why “Augun” and not just “Augu”? What does the -n ending do?

Augu is the bare plural noun “eyes.”
Augun is the definite form: “the eyes.”

In Icelandic, the definite article is usually a suffix, not a separate word:

auga – an eye → augat / augað – the eye (sg. neuter)
augu – eyes → augun – the eyes (pl. neuter)

So Augun hennar literally is “the eyes of her”, which corresponds to English “her eyes.”

What is the subject of “verða” and why is the verb in the plural?

The subject is Augun hennar (her eyes).

Since augun is plural, the verb verða is also plural (3rd person plural present):

Augun hennar verða stór. – Her eyes become big / go wide.
Augað hennar verður stórt. – Her eye becomes big / goes wide. (singular)

Verb–subject agreement in number works similarly to English, but with more visible endings in some tenses.

Why is the verb “verða” used instead of “vera”? What nuance does it have?

vera = to be (state)
verða = to become, to get, to turn (change of state)

In Augun hennar verða stór, the idea is that the eyes change from normal to wide:

Augun hennar eru stór. – Her eyes are big (by nature / permanently).
Augun hennar verða stór. – Her eyes become big / go wide (at that moment).

So verða expresses a transformation or a reaction.

Why is “stór” not plural‑looking (like stórir or stórar) even though “Augun” is plural?

Adjectives in Icelandic agree with the noun in gender, number, and case.

Here:

augun is neuter plural nominative definite
In predicative position (after vera / verða etc.), the adjective takes neuter plural nominative too.

For stór:

masc. pl. nom.: stórir
fem. pl. nom.: stórar
neut. pl. nom.: stór

So “Augun hennar verða stór” is exactly the correct plural agreement; the neuter plural form just happens to look like the basic dictionary form.

What does “þegar” do here, and how is the word order in the þegar‑clause different from main clauses?

þegar is a subordinating conjunction meaning “when” (in the sense of whenever / at the time that).

Main clause word order is typically V2 (verb in second position):
- Hún sér uppáhalds leikfangið sitt.
  (She sees her favorite toy. – verb in second position: sér)
Subordinate clause after þegar:
- þegar hún sér uppáhalds leikfangið sitt
  Here þegar comes first, and then word order is subject–verb–object:
  - subject: hún
  - verb: sér
  - object: uppáhalds leikfangið sitt

You do not move the verb to the second overall position after þegar; it stays after the subject inside the clause.

What form is “sér”, and is it a reflexive verb here?

sér is the 3rd person singular present indicative of the verb að sjá (to see).

Principal forms:

infinitive: að sjá
1st sg. pres.: ég sé
3rd sg. pres.: hún sér – she sees
past: sá
past participle: séð

Here sér is not reflexive; it simply means “sees.”
The reflexive element is expressed separately by sitt (her own) later in the sentence, not by the verb form.

Why doesn’t “uppáhalds” change its form? Shouldn’t adjectives also decline?

Most Icelandic adjectives decline, but uppáhalds is a common exception: it is indeclinable in modern usage.

So you say:

uppáhalds leikfangið – the favorite toy
uppáhalds bókin – the favorite book
uppáhalds myndirnar – the favorite movies

In all genders, numbers, and cases, uppáhalds usually stays the same. Historically it relates to a genitive form, which is why it ends in -s, but learners can safely treat it as not changing.

Why is “leikfangið” definite (“the toy”) even though we already mark possession with “sitt”?

In Icelandic, definiteness (“the”) and possession (“my/your/her own”) are separate things and are often both marked:

leikfang – a toy
leikfangið – the toy
leikfangið hennar – her toy (the toy of her)
leikfangið sitt – her own toy (the toy that belongs to the subject)

So:

The -ið ending on leikfangið makes it definite.
The pronoun sitt shows whose it is and that the owner is the subject of the clause (hún).

Having both is normal and not considered redundant in Icelandic.

What is the difference between “leikfangið sitt” and “leikfangið hennar”?

Both mean “her toy”, but with an important nuance:

leikfangið sitt – her own toy
- Uses the reflexive possessive (sinn/sín/sitt).
- Refers back to the subject of the same clause (here hún).
- Implies the toy belongs to her, not to someone else in the context.
leikfangið hennar – her toy (non‑reflexive)
- Uses hennar.
- Refers to some female person who is not necessarily the subject.
- In this sentence it could be ambiguous: it might be someone else’s toy that she sees.

So in þegar hún sér uppáhalds leikfangið sitt aftur, sitt tells us that the toy belongs to the same “she” who is doing the seeing.

Why is “sitt” placed after “leikfangið” and not before, like “sitt leikfang”?

Both orders are grammatically possible in Icelandic:

uppáhalds leikfangið sitt
uppáhalds sitt leikfang

However, the most natural and common order is:

any adjectives (here uppáhalds),
the noun in definite form (leikfangið),
then the post‑posed possessive (sitt / hennar / etc.).

So:

uppáhalds leikfangið sitt is the standard, neutral phrase.
uppáhalds sitt leikfang is understandable but feels more marked or less natural in everyday speech.

Why is “aftur” at the very end, and can it go elsewhere?

aftur means “again.” It is commonly placed late in the clause, often near the verb or at the end:

Hún sér leikfangið sitt aftur.
Hún sér aftur leikfangið sitt. (also possible, slightly different emphasis)

In the full sentence, ending with aftur is very natural:

þegar hún sér uppáhalds leikfangið sitt aftur.

Putting aftur earlier (þegar hún aftur sér…) would sound odd or poetic. So its position here is standard and idiomatic.