Learn Hardcore Icelandic: Hún sefur alltaf undir sama teppi. - She always sleeps under the same blanket.

Hún – 3rd person singular feminine pronoun in the nominative case: she (or it, if referring to a feminine noun). It’s the subject.
sefur – 3rd person singular present tense of the verb sofa (to sleep).
alltaf – adverb meaning always; it modifies the verb sefur.
undir – preposition meaning under, used with the dative case here.
sama – the adjective sami (same), here in the dative singular neuter form, agreeing with teppi.
teppi – neuter noun in the dative singular, meaning blanket.

So the core structure is: Subject (Hún) – Verb (sefur) – Adverb (alltaf) – Prepositional phrase (undir sama teppi).

Why is the verb sefur and not something more like the infinitive sofa?

sofa is the infinitive form: to sleep. In Icelandic, you have to conjugate it for person and number.

Present tense of sofa is:

ég sef – I sleep
þú sefur – you (sg) sleep
hann / hún / það sefur – he / she / it sleeps
við sofum – we sleep
þið sofið – you (pl) sleep
þeir / þær / þau sofa – they sleep

In your sentence, the subject is hún (she), so you need the 3rd person singular present form sefur. Using sofa here (Hún sofa alltaf…) would be ungrammatical.

What tense or aspect does sefur express here? Is this like English “sleeps” or “is sleeping”?

sefur is simple present tense. Icelandic present can cover both:

English simple present (habitual): She always sleeps under the same blanket.
English present progressive (right now): She is sleeping under the same blanket.

Context decides which reading makes most sense. Because of alltaf (always), this sentence is naturally read as a habitual action, like English She always sleeps under the same blanket.

Why does alltaf go after sefur and not before, like English always sleeps?

In Icelandic main clauses, the finite verb usually comes in second position (the so‑called V2 rule), and adverbs like alltaf commonly come right after the verb:

Hún sefur alltaf undir sama teppi. – She always sleeps under the same blanket.

You can move alltaf for emphasis, but the verb still tends to stay in second position:

Alltaf sefur hún undir sama teppi. – Always she sleeps under the same blanket. (emphasis on always)
Hún sefur undir sama teppi alltaf. – possible, but sounds more marked; the neutral place is right after the verb.

So [subject] + [verb] + [adverb] is the most typical neutral pattern.

What case is teppi in here, and why?

teppi is in the dative singular.

The reason: the preposition undir can take either accusative or dative:

accusative – when there is motion to a position (change of location)
dative – when something is in a position (static location)

In this sentence, she is simply located under the blanket while sleeping, not moving there:

Hún sefur alltaf undir sama teppi.
→ static location → undir
- dative → teppi (dative sg)

If there were motion to that place, you would use accusative, e.g.:

Hún fer undir sama teppi. – She goes under the same blanket. (motion → accusative)

If teppi is dative, why doesn’t it change its form? It still looks like teppi.

Many neuter nouns in Icelandic have the same form for nominative, accusative, and dative singular. teppi is one of them.

Typical declension of teppi (blanket):

Singular:
- nominative: teppi
- accusative: teppi
- dative: teppi
- genitive: teppis
Plural:
- nominative: teppi
- accusative: teppi
- dative: teppum
- genitive: teppa

So in undir sama teppi, the case is dative, but it’s visible only in the adjective sama, not in the noun’s ending.

Why is it sama teppi and not sami teppi?

The adjective sami (same) has to agree with the noun it modifies in:

gender
number
case

Here, teppi is:

gender: neuter
number: singular
case: dative (after undir, in a static sense)

The correct form of sami for dative singular neuter is sama.

So:

undir sama teppi – under the same blanket (dat. sg. neut.)
Not: undir sami teppi (wrong agreement)

In English we say “the same blanket”. Why is there no word for “the” in sama teppi?

Icelandic does not have a separate word for the definite article “the”; it normally attaches it as an ending:

teppi – a blanket / blanket
teppið / teppinu – the blanket (nom/acc / dat)

However, some determiners and adjectives (like sami, sá, þessi) themselves carry a kind of definite meaning and are not normally combined with the suffixed article. With sami, you generally do not say:

undir sama teppinu ✗

The definiteness is already expressed by sama:

undir sama teppi ≈ under the same blanket

So even though English has “the same blanket”, Icelandic expresses that definiteness through sama, not through an extra ending on teppi.

Could Hún here refer to an object, not a woman? How does gender work?

Yes, hún can refer to:

a female person: Hún sefur… – She sleeps…
or any grammatical feminine noun, regardless of biological gender.

For example:

Bókin er á borðinu. Hún er ný.
– The book is on the table. It (she) is new.
(bók is grammatically feminine, so the pronoun is hún.)

In your sentence, without context we usually imagine hún as she (a female person), but grammatically it could be any feminine referent previously mentioned.

Can I change the word order, like Alltaf sefur hún undir sama teppi? Is that correct?

Yes, that is grammatically correct.

Some variants (all correct, but with slightly different emphasis):

Hún sefur alltaf undir sama teppi.
– Neutral, everyday word order.
Alltaf sefur hún undir sama teppi.
– Emphasizes always; sounds more stylistic or contrastive.
Undir sama teppi sefur hún alltaf.
– Emphasizes under the same blanket (e.g., if contrasting with others).

In all cases, the finite verb sefur tends to stay in second position, which is important for Icelandic main clauses.

How would I say “She always slept under the same blanket” in the past tense?

You need the simple past (preterite) of sofa, which is svaf in 3rd person singular:

Hún svaf alltaf undir sama teppi.
– She always slept under the same blanket.

Only the verb changes; the rest of the sentence stays the same.

Why do we use undir and not some other word for “under”? Is there any nuance?

undir is the regular, everyday preposition used for under / beneath in a spatial sense:

undir borðinu – under the table
undir rúminu – under the bed
undir teppinu / teppi – under the blanket

Other related words:

neðan við – literally “below”, often used with a reference point (neðan við húsið – below the house)
fyrir neðan – down below, further down

In the context of physically being under a blanket while sleeping, undir is the normal choice: undir sama teppi.

Where would I put a negation, for example never or not always?

Negation adverbs also tend to come right after the verb, in the same slot as alltaf. Compare:

Hún sefur alltaf undir sama teppi.
– She always sleeps under the same blanket.
Hún sefur aldrei undir sama teppi.
– She never sleeps under the same blanket.

For not always, you normally keep alltaf near the verb as well:

Hún sefur ekki alltaf undir sama teppi.
– She does not always sleep under the same blanket.

So the pattern is usually: subject – verb – negation/adverb – rest.

How is the sentence Hún sefur alltaf undir sama teppi pronounced?

Approximate pronunciation (using IPA):

Hún – [huːn]
sefur – [ˈsɛːvʏr]
alltaf – [ˈal̥ːtaːv] (double l is long; final f is often [v])
undir – [ˈʏntɪr] (the d is often not clearly pronounced as [d])
sama – [ˈsaːma]
teppi – [ˈtʰɛhpɪ] (aspirated t, and pp is a strong, long consonant)

Stress is always on the first syllable of each word:

HÚN sefur ALLtaf UNdir SAma TEPpi.