Urðunin er dýr.

In Icelandic, the definite article is usually attached to the end of the noun instead of standing as a separate word.

• urðun = landfill / disposal / burial (indefinite)
• urðunin = the landfill / the disposal / the burial (definite)

So -in here is the attached definite article.

The basic form is urðun.

In the sentence, it appears as urðunin, which is the definite singular form. So if you were looking it up in a dictionary, you would usually search for urðun, not urðunin.

Urðun is a feminine noun.

That matters because adjectives in Icelandic often agree with the noun in gender, number, and case. In this sentence, dýr is describing urðunin, so its form matches a feminine singular nominative subject.

It actually is in the correct agreeing form already.

After the verb er (is), Icelandic predicate adjectives still agree with the subject. Since urðunin is feminine singular, the correct form here is dýr.

Compare:

• Urðunin er dýr. = feminine singular
• Húsið er dýrt. = neuter singular
• Bílarnir eru dýrir. = masculine plural

So dýr is not the default form for every situation; it is the right form for this noun.

Er is the 3rd person singular present form of the verb að vera (to be).

So:

• ég er = I am
• þú ert = you are
• hann / hún / það er = he / she / it is

In Urðunin er dýr, the subject is singular, so er is the correct form.

This is the normal Icelandic pattern for a simple statement:

subject + verb + complement

So:

• Urðunin = subject
• er = verb
• dýr = complement adjective

This works very much like English The landfill is expensive.

You can move words around in Icelandic for emphasis, but this sentence is the neutral, standard order.

You know from the sentence structure.

In Urðunin er dýr, the word after er is describing the subject, so dýr is functioning as an adjective meaning expensive.

That is important because dýr can also appear in other roles in Icelandic, but here the grammar clearly shows it is an adjective.

A rough pronunciation guide is:

UR-thu-nin

A few helpful points:

• u is pronounced somewhat like the Icelandic rounded u, not exactly like English oo
• ð is like the th in this, not the th in thing
• the stress is usually on the first syllable

So the first part, urð-, has that voiced th sound.

A rough guide is:

deer — but with an Icelandic vowel quality

More exactly:

• ý is pronounced roughly like ee
• r is pronounced with an Icelandic r, not necessarily like an English r

So for an English speaker, deer is a useful approximation, though not perfect.

It is a very common word for expensive, yes.

For example:

• Þetta er dýrt. = This is expensive.
• Bíllinn er dýr. = The car is expensive.

But be aware that Icelandic words can have more than one meaning depending on context, so you should always pay attention to how the word is being used in the sentence.

It is in the nominative case.

That is because it is the subject of the sentence. In simple equational sentences like X is Y, the subject is normally nominative:

• Urðunin = nominative subject
• er dýr = predicate describing the subject

Usually, Icelandic uses the attached definite article, as in urðunin.

A separate demonstrative-like word such as þessi can be used, but that means something more like this rather than a plain English the:

• urðun = landfill / disposal
• urðunin = the landfill / the disposal
• þessi urðun = this landfill / this disposal

So in your sentence, the attached ending is the normal choice.

Grammatically, yes — that would make the noun indefinite instead of definite.

So the difference is:

• Urðunin er dýr. = The landfill/disposal is expensive.
• Urðun er dýr. = Landfill/disposal is expensive or A landfill/disposal is expensive, depending on context

Icelandic does not have an indefinite article like English a/an, so the bare noun can often cover that meaning.

Yes, in this kind of sentence it normally does, because dýr is not directly attached to the noun inside a noun phrase. It is part of the predicate after er.

Compare:

• urðunin er dýr = the landfill is expensive
• dýr urðun = an expensive landfill / expensive disposal

So when the adjective is linked by er, it comes after the verb as part of the predicate.

Yes — this is one of the most basic and useful Icelandic sentence patterns:

[noun with or without article] + er + [adjective]

For example:

• Bíllinn er stór. = The car is big.
• Bókin er góð. = The book is good.
• Húsið er dýrt. = The house is expensive.

Just remember that the adjective may change form to agree with the noun.