Netnámskeiðið er mjög gott.

The ending -ið is the definite article attached to the noun.

In Icelandic, “the” is usually not a separate word; instead, it is added to the end of the noun:

• netnámskeið = an online course / online course
• netnámskeiðið = the online course

Grammatically:

• -ið here marks:
  • singular
  • nominative case
  • neuter gender

Icelandic loves compound words: it often combines several words into one.

Netnámskeiðið is made up of:

• net = internet, net
• nám = study, learning
• skeið = course, period
• -ið = the definite article “the”

So literally: net + nám + skeið + ið → the internet-study-course → the online course.

Writing this as one word is completely normal in Icelandic.

Approximate pronunciation:

• Netnámskeiðið ≈ NET-noums-kay-thith
• er ≈ ehr (like “air” with a shorter vowel)
• mjög ≈ myuhg (like my
  • very short uh
    • soft gh)
• gott ≈ goht (with a short o, a bit like “got”, and a slight h-sound before the final t)

More precise (IPA-style) approximation:

• Netnámskeiðið → /ˈnɛtˌnaumsˌsceiðɪð/
• er → /ɛr/
• mjög → /mjœːɣ/
• gott → /kɔht/

Key sounds to notice:

• ð (in -ið) is like the “th” in “this” (voiced).
• tt in gott is pronounced roughly like ht.
• mjög has a front rounded vowel œː, often approximated by English speakers as something between “myuh” and “muuuh” plus a soft gh at the end.

Er is the present tense form of “to be” used with 3rd person singular subjects:

• ég er – I am
• þú ert – you (sing.) are
• hann / hún / það er – he / she / it is
• við erum – we are
• þið eruð – you (pl.) are
• þeir / þær / þau eru – they are

Since Netnámskeiðið (the online course) is singular, we use er:

• Netnámskeiðið er mjög gott.
  → The online course is very good.

The adjective must agree with the noun in:

• gender
• number
• case

The base adjective is góður (good). Its main nominative singular forms are:

• góður – masculine
• góð – feminine
• gott – neuter

The noun netnámskeið is:

• neuter,
• singular,
• nominative (subject of the sentence).

So the correct form is gott:

• Netnámskeiðið er mjög gott.

The sentence uses the normal subject–verb–complement order:

• Netnámskeiðið (subject)
• er (verb)
• mjög gott (adverb + adjective as complement)

So:

Netnámskeiðið er mjög gott.
The online course is very good.

You can move parts around for emphasis, but that sounds more marked or poetic:

• Mjög gott er netnámskeiðið.
  → Emphasises “very good”; not the neutral everyday way to say it.

For normal speech, keep Netnámskeiðið er mjög gott.

Mjög means “very”. It is an adverb, and it does not decline:

• mjög gott – very good
• mjög góð – very good (feminine)
• mjög góðir – very good (masc. plural)

In all of these, mjög stays the same; only the adjective that follows changes.

Some similar intensifiers (also indeclinable) are:

• virkilega – really
• rosalega – terribly / really (colloquial)
• frekar – rather / quite

You need the plural definite form of the noun and plural agreement on the adjective and verb:

• Netnámskeiðin eru mjög góð.

Breakdown:

• Netnámskeið – online course
• Netnámskeiðin – the online courses (neuter plural definite)
• eru – are (3rd person plural of vera, to be)
• góð – good (neuter plural form; nominative)

So:

• Netnámskeiðið er mjög gott. – The online course is very good.
• Netnámskeiðin eru mjög góð. – The online courses are very good.

The difference is indefinite vs definite:

• Netnámskeið er mjög gott.
  → An online course is very good / An online course is very good (in general).

• Netnámskeiðið er mjög gott.
  → The online course is very good (a specific course we both know about).

Icelandic shows this mostly with the suffix article:

• no article: netnámskeið → a(n) online course
• definite article: netnámskeiðið → the online course

You add ekki (not) after the verb er:

• Netnámskeiðið er ekki mjög gott.
  → The online course is not very good.

Word order:

• Netnámskeiðið – subject
• er – verb
• ekki – negation
• mjög gott – complement

A couple of clues:

1. The definite form Netnámskeiðið ends in -ið, which is a very common neuter singular nominative definite ending.
2. Many Icelandic nouns ending in -ið in the definite singular are neuter (though not all such endings are neuter, this is a strong pattern).

In dictionaries you will often see it given as:

• netnámskeið, -s, - (n.)

The n. indicates neuter (hvorugkyn).

Yes, but then the structure changes slightly. For “a very good online course” you would say:

• mjög gott netnámskeið

Here:

• gott is before the noun
• the noun is indefinite (no -ið)
• both gott and netnámskeið are in neuter singular nominative and agree in gender/number/case.

Compare:

• Mjög gott netnámskeið. – A very good online course.
• Netnámskeiðið er mjög gott. – The online course is very good.

Same words, but the position of the article and the role in the sentence are different.