Learn Hardcore Icelandic: Í góðu brúðkaupi er mikil gleði og lítil sorg. - In a good wedding there is much joy and little sorrow.

Accusative = movement into something
- Ég fer í húsið. – I go into the house.
Dative = location / state in something
- Ég er í húsinu. – I am in the house.

In the sentence Í góðu brúðkaupi er mikil gleði og lítil sorg, we are talking about what is in a good wedding (a state/location, not movement).
So í governs the dative case, and the noun appears as brúðkaupi (dative singular), not brúðkaup.

Why does brúðkaup change to brúðkaupi?

Brúðkaup is a neuter noun meaning “wedding (ceremony)”. Its singular declension is roughly:

Nominative: brúðkaup – (a) wedding
Accusative: brúðkaup – (I see) a wedding
Dative: brúðkaupi – (in/at) a wedding
Genitive: brúðkaups – of a wedding

Because í here requires the dative (location), we have to use the dative singular form:

í brúðkaupi = in a wedding

That’s why we see the -i ending.

Why is the adjective góður in the form góðu in í góðu brúðkaupi?

Adjectives in Icelandic must agree with the noun in:

Gender (masculine / feminine / neuter)
Number (singular / plural)
Case (nominative / accusative / dative / genitive)
And also definiteness (indefinite/definite pattern)

Here:

Noun: brúðkaupi
- Gender: neuter
- Number: singular
- Case: dative (after í)

The adjective is góður (“good”). The form that matches neuter, singular, dative, indefinite is:

góðu

So we get:

í góðu brúðkaupi – in a good wedding
(neut. sg. dat.: góðu brúðkaupi)

Compare:

Nominative neuter sg.: gott brúðkaup – a good wedding
Dative neuter sg.: í góðu brúðkaupi – in a good wedding

Why is there no word for “a” or “the” in í góðu brúðkaupi?

Icelandic does not have a separate indefinite article like English “a/an”. Indefiniteness is just absence of definiteness.

Definiteness is usually marked by a suffix on the noun (and sometimes a special “definite” form of the adjective). So:

í góðu brúðkaupi
Literally: in good wedding
Meaning: in a good wedding / in a good wedding (in general)

To say “in the good wedding”, you would normally use a definite form, for example:

With a definite noun ending:
- í góðu brúðkaupinu – in the good wedding
  - brúðkaupinu = the wedding (neuter dat. sg. definite)
Or (more formal/literary) with a separate definite article:
- í hinu góða brúðkaupi – also in the good wedding

So the sentence as given is indefinite / generic: talking about what (typically) happens in a good wedding.

Why do we use mikil with gleði and lítil with sorg? Why not mikið / margt or lítill?

First, note the nouns:

gleði – joy
sorg – sorrow

Both are treated here as singular, feminine, uncountable nouns (like English “joy”, “sorrow”, “water”, “music”).

The adjectives:

mikill – much / big (as an adjective)
- Feminine nominative singular: mikil
lítill – little / small (as an adjective)
- Feminine nominative singular: lítil

Since both gleði and sorg are:

Feminine
Singular
In nominative case (they are the things that “are”)

the adjectives must match: fem. sg. nominative:

mikil gleði – much joy / great joy
lítil sorg – little sorrow

Why not mikið?

Mikið is the neuter form (or adverbial “a lot”), so it would not agree with gleði (feminine).

Why not margar (“many”)?

Margar is used for countable plural feminine nouns (e.g. “many books”).
Gleði and sorg here are uncountable (mass) nouns, so we talk about much (mikil / lítil), not many.

Are gleði and sorg singular or plural here, and what gender are they?

Here they are both singular and function as mass (uncountable) nouns:

gleði – joy
- Gender: feminine
- Often indeclinable or only slightly declined in modern use.
sorg – sorrow, grief
- Gender: feminine
- Regularly declined.

Because they are feminine singular nominative, they take:

mikil (fem. sg. nom.) gleði
lítil (fem. sg. nom.) sorg

There is no plural idea here; it’s like English “much joy and little sorrow”, not “joys” and “sorrows”.

Why is it er and not eru when there are two things: mikil gleði og lítil sorg?

Literally, the structure is similar to English “there is much joy and little sorrow”, where English also uses is, not are, even though two nouns follow.

In Icelandic:

er = is (3rd person singular)
eru = are (3rd person plural)

In existential-type sentences of this sort, especially with abstract / mass nouns and a kind of general description, Icelandic very often uses the singular verb:

Í góðu brúðkaupi er mikil gleði og lítil sorg.
In a good wedding there is much joy and little sorrow.

You will also hear Icelandic where the verb agrees more straightforwardly in number, but here the singular “er” is the normal, idiomatic choice, much like English “there is joy and sorrow”.

Why does the sentence start with Í góðu brúðkaupi instead of with the “subject” (mikil gleði og lítil sorg)?

Icelandic is a verb-second (V2) language in main clauses: the finite verb (here, er) typically appears in second position, and exactly one element comes before it (subject, object, adverbial phrase, etc.).

In this sentence:

Í góðu brúðkaupi – a prepositional phrase (adverbial, “in a good wedding”)
er – finite verb, 2nd position
mikil gleði og lítil sorg – the rest of the clause

So the word order follows the V2 rule:

[Adverbial] + [Verb] + [Subject / predicate]

Starting with Í góðu brúðkaupi also puts the situation / setting in focus:
In a good wedding, what is there? → much joy and little sorrow.

Can I put the sentence in another word order, and would that still be correct?

Yes, you can change the word order while keeping the verb in second position. For example:

Mikil gleði og lítil sorg er í góðu brúðkaupi.

This is grammatically fine. The nuance:

Í góðu brúðkaupi er mikil gleði og lítil sorg.
→ puts more emphasis on the setting (“In a good wedding, there is…”).
Mikil gleði og lítil sorg er í góðu brúðkaupi.
→ puts more emphasis on the joy and sorrow (“Much joy and little sorrow are in a good wedding.”).

Both sound natural, but the original version is very idiomatic for a general statement about what characterizes a good wedding.

How would the sentence change if I want to say “In good weddings (plural), there is much joy and little sorrow”?

Now the location phrase becomes plural dative:

Singular dative: í góðu brúðkaupi – in a good wedding
Plural dative: í góðum brúðkaupum – in good weddings

So a natural plural version is:

Í góðum brúðkaupum er mikil gleði og lítil sorg.
In good weddings there is much joy and little sorrow.

Notice:

góðum = plural dative of góður (agreeing with brúðkaupum)
brúðkaupum = dative plural of brúðkaup

You could also choose eru instead of er if you want clearer plural agreement, but er is still common and idiomatic in such general, existential statements.

How do you pronounce brúðkaupi, gleði, and sorg?

Approximate pronunciation (using IPA and rough English hints):

brúðkaupi – “in a wedding” (dative form)
- IPA: [ˈbruːðˌkʰœiːpɪ] (approx.)
- Roughly: BROOTH-kœyp-ih
  - brúð: bruuth (like “brewth”; ð = soft “th” in this)
  - kaup: like “kœyp”, with a vowel between uh and French œ
    - ee glide
  - final -i: short “i” as in bit
gleði – joy
- IPA: [ˈklɛːðɪ]
- Roughly: GLEH-thi
  - g is pronounced like a hard g, often with slight g–l cluster sounding close to “g-leh”
  - ð again is the soft “th” in this
  - final -i: short “i” as in bit
sorg – sorrow
- IPA: [sɔrk] (final g is often devoiced and may sound like k)
- Roughly: sork (with o like in British “sauce” but shorter)

These are approximations; Icelandic has some subtle vowel qualities and consonant clusters that don’t exist in English, but this should get you close enough to be understood.