Learn Hardcore Icelandic: Þrír hestar eru í garðinum.

hestur (horse) is masculine.
In this sentence, Þrír hestar is the subject, so it’s in the nominative plural.
The masculine nominative plural form of “three” is þrír.

The main nominative forms of “three” are:

þrír – masculine (e.g. þrír hestar – three horses)
þrjár – feminine (e.g. þrjár konur – three women)
þrjú – neuter (e.g. þrjú hús – three houses)

So it must be Þrír hestar, not þrjár hestar or þrjú hestar.

Why is it hestar and not hestur?

In Icelandic, nouns change form for number and case.

hestur is the singular nominative: one horse.
hestar is the plural nominative: horses (subject form).

Since the sentence talks about three horses, the noun must be plural:

Einn hestur er í garðinum. – One horse is in the yard.
Þrír hestar eru í garðinum. – Three horses are in the yard.

Using Þrír hestur would mix plural þrír with singular hestur, which is ungrammatical.

Why is the verb eru instead of er?

Er and eru are singular vs. plural forms of the verb að vera (to be):

er – 3rd person singular: he/she/it is
eru – 3rd person plural: they are

Since the subject Þrír hestar is plural, the verb must also be plural:

Hesturinn er í garðinum. – The horse is in the yard.
Hestarnir eru í garðinum. – The horses are in the yard.
Þrír hestar eru í garðinum. – Three horses are in the yard.

I would say “There are three horses in the yard” in English. Where is the word “there” in the Icelandic sentence?

Icelandic usually does not use an extra word like English there in existential sentences.

English:

There are three horses in the yard.

Icelandic just uses a normal subject–verb–place structure:

Þrír hestar eru í garðinum. – literally Three horses are in the yard.

If you really want to add something like there, you can add an adverb (often for emphasis), but it’s not required:

Það eru þrír hestar í garðinum. – literally It/there are three horses in the yard.
(This is also correct and often used.)

The basic sentence Þrír hestar eru í garðinum already covers the meaning of there are three horses.

Why is it í garðinum and not í garðinn or just í garði?

This is about prepositions and case:

The preposition í (in) can take either:
- dative → for location (where something is)
- accusative → for motion into (where something is going)
In this sentence, the horses are located in the yard, not moving into it, so í takes the dative.

For garður (yard/garden), the relevant forms are:

Nominative singular: garður
Accusative singular: garð
Dative singular: garði
Definite dative singular: garðinum

So:

Í garðinum – in the yard (location, dative, definite)
Í garðinn – into the yard (motion into, accusative, definite)

Here we want location, so í garðinum is correct.

What does the ending -inum on garðinum mean?

The ending -inum is the definite article attached to the noun and also shows case:

garður – a yard / a garden (indefinite)
garðurinn – the yard (nominative, definite)
garðinum – the yard (dative, definite)

So garðinum tells you two things:

The noun is definite: the yard, not just a yard.
It is in the dative singular, because of the preposition í indicating location.

So í garðinum = in the yard.

Is Ţrír hestar definite or indefinite? How would I say “the three horses are in the yard”?

Þrír hestar is indefinite: three horses (not specified which ones).

To say “the three horses”, you make the noun definite, but you leave the numeral indefinite:

Þrír hestar eru í garðinum. – Three horses are in the yard. (some three horses)
Þrír hestarnir eru í garðinum. – The three horses are in the yard. (specific, known ones)

Notice:

hestar → hestarnir (definite plural nominative)
The number þrír does not take a definite ending. Definite marking is on the noun.

Can I change the word order to Í garðinum eru þrír hestar? Is that still correct?

Yes, that word order is also correct and quite natural.

Both are grammatical:

Þrír hestar eru í garðinum.
Í garðinum eru þrír hestar.

The difference is mainly in emphasis:

Þrír hestar eru í garðinum.
Neutral focus on three horses as the subject.
Í garðinum eru þrír hestar.
Slight emphasis on the location first – In the yard, there are three horses (as opposed to somewhere else, or as new information about the yard).

Icelandic word order is flexible, especially with adverbials like í garðinum, but the verb generally stays in second position in main clauses.

How do I pronounce Þrír and garðinum? The letters Þ and ð confuse me.

Þrír

Þ is like English unvoiced th in thing.
Then comes r (rolled or tapped).
í is a long ee sound.
Final r is pronounced (rolled/tapped).

Approximate: [thr eer], with a clear trilled r.

garðinum

ga-: g as in go, a like the a in father (shorter).
rð: the ð is like a voiced th in this, but often softened in fast speech; r is rolled/tapped.
i in -ði-: short i, like i in bit.
-num: n
- u like oo in book, m at the end.

The letter ð (called eð) is usually voiced th (as in this). The letter Þ (thorn) is unvoiced th (as in thing).

What is the difference between garður meaning “garden” and “yard”? How do I know which one is meant?

Icelandic garður can cover several related ideas:

a yard (around a house)
a garden
a courtyard
sometimes even a park, depending on context and compounds

English separates yard and garden more strictly, but Icelandic doesn’t always.

Which English word you choose depends on:

Context:
- Around a house in a suburban setting → often yard.
- With plants, flowers, vegetables → often garden.
Common collocations:
- bakgarður – backyard
- grasgarður – (more like) grass garden/park
- garðurinn hjá húsinu – the yard/garden by the house (either translation could work depending on the situation).

In isolation, í garðinum could reasonably be translated as either in the yard or in the garden.

Why isn’t þrír declined for case here? Don’t numbers change case in Icelandic?

Numbers do decline for case, but in this sentence þrír is already in the nominative case, which matches its role as subject.

For masculine “three”, the main singular-case forms are:

Nominative: þrír
Accusative: þrjá
Dative: þrem or þremur
Genitive: þriggja

Some examples:

Ég sé þrjá hesta. – I see three horses. (accusative)
Ég tala við þrjá hesta. – I talk to three horses. (accusative)
Ég gef þrem hestum að borða. – I feed three horses. (dative)
Ég hugsa um þrjá hesta. – I think about three horses. (accusative)

In Þrír hestar eru í garðinum, þrír hestar is the subject in nominative, so þrír is in its nominative form.

Is Þrír hestar definitely the subject here? It feels a bit like just a number phrase.

Yes, Þrír hestar is the grammatical subject of the sentence.

You can check this by:

Verb agreement:
- The verb eru is 3rd person plural, agreeing with hestar.
Position:
- In the neutral word order, the subject usually comes before the verb in Icelandic main clauses:
  [Subject] [Verb] [Other stuff] → Þrír hestar eru í garðinum.

So grammatically:

Subject: Þrír hestar
Verb: eru
Prepositional phrase (location): í garðinum

Even though Þrír is just a number, together with hestar it forms the full subject phrase.

How would the sentence look in the past tense or future tense?

Using the same structure, just changing the verb að vera (to be):

Past tense (were):
Þrír hestar voru í garðinum. – Three horses were in the yard.
Present perfect (have been):
Þrír hestar hafa verið í garðinum. – Three horses have been in the yard.
Future (will be):
Icelandic doesn’t have a special future tense of vera; it often uses munu
- infinitive:
  Þrír hestar munu vera í garðinum. – Three horses will be in the yard.

The noun and numeral (Þrír hestar) and the prepositional phrase (í garðinum) stay the same; only the verb form changes.