Ég klúðraði heimilisfanginu.

Because að klúðra normally takes the dative case in Icelandic.

So the noun heimilisfang changes form:

• heimilisfang = an address / address
• heimilisfangi = to/with an address, or an address in the dative indefinite
• heimilisfanginu = the address in the dative singular

English learners often expect a direct object here, but Icelandic verbs do not always work that way. Some verbs simply require a certain case, and klúðra is one of the verbs that takes dative.

The ending -inu shows two things at once:

1. the noun is singular dative
2. it is definite: the address

Icelandic usually puts the as a suffix on the noun instead of using a separate word.

So:

• heimilisfangi = an address / an address in the dative
• heimilisfanginu = the address

Also, heimilisfang is a neuter noun, and this ending fits the neuter singular dative definite form.

Because klúðraði is the 1st person singular past form of að klúðra.

The sentence has ég = I, so the verb needs the matching form:

• ég klúðra = I mess up / I botch
• ég klúðraði = I messed up / I botched

The ending -ði is a very common past-tense ending for weak verbs in Icelandic.

The dictionary form is að klúðra.

In dictionaries, Icelandic verbs are usually listed with að + infinitive:

• að klúðra = to mess up, to botch

From that you get forms like:

• ég klúðra = I mess up
• ég klúðraði = I messed up

So if you want to look the verb up, search for klúðra, not klúðraði.

It is a very common everyday word, but it has a somewhat informal feel.

It often means things like:

• mess up
• botch
• screw up

So Ég klúðraði heimilisfanginu sounds natural in conversation. In a more formal style, a speaker might choose a different verb depending on context, but klúðra is extremely useful and common.

Because Icelandic usually expresses the by attaching it to the end of the noun.

That is what happens in heimilisfanginu:

• heimilisfang = address
• heimilisfangið = the address
• heimilisfanginu = the address, but in the dative case

So instead of a separate word like English the, Icelandic often uses a suffixed definite article.

Yes, this sentence uses the very common basic pattern:

• Ég = subject
• klúðraði = verb
• heimilisfanginu = object/complement required by the verb

So the order is basically Subject – Verb – Object, which feels familiar to English speakers.

However, Icelandic word order can change more freely than English because case endings help show each word’s role. But in a simple statement like this, the order is very straightforward.

Usually, no. Icelandic normally keeps the subject pronoun.

So:

• Ég klúðraði heimilisfanginu = normal
• leaving out ég would usually sound incomplete unless the context is very special, such as notes, diary style, or certain informal situations

Unlike languages such as Spanish or Italian, Icelandic does not regularly drop subject pronouns in ordinary sentences.

Heimilisfang is a neuter noun, and yes, that matters.

Gender affects:

• the noun’s endings
• the form of the suffixed article
• adjective agreement if adjectives are added

Here, the neuter gender is part of why the definite dative singular form is heimilisfanginu.

If it were a noun of another gender, the ending would be different.

It would be:

Ég klúðra heimilisfanginu.

That means I mess up the address or I’m messing up the address, depending on context.

So compare:

• Ég klúðra heimilisfanginu. = present
• Ég klúðraði heimilisfanginu. = past

A rough learner-friendly pronunciation is something like:

yeg KHLU-thra-thi

A few helpful notes:

• é in Ég sounds like ye in yes
• klú has a long oo-like vowel
• ð is like the th in this, not the th in thin
• the r in klúðraði is an Icelandic r, typically trilled or tapped

The exact Icelandic pronunciation is subtler than English spelling can show, but the key point is that ð is voiced, like in this.