Learn Hardcore Icelandic: Ég er ekki lengur hræddur þegar ljósin eru kveikt. - I am no longer afraid when the lights are on.

Ég – I
er – am (1st person singular of vera, “to be”)
ekki – not
lengur – longer / any longer / anymore
hræddur – afraid (masculine singular form)
þegar – when
ljósin – the lights (ljós “light” + -in definite plural ending = “the lights”)
eru – are (3rd person plural of vera)
kveikt – lit / turned on (past participle of kveikja, “to switch on, light”)

So the structure is literally: I am not longer afraid when the‑lights are lit.

Why is it hræddur and not just hrædd or hrætt?

In Icelandic, adjectives used with vera (“to be”) agree with the subject in:

gender (masculine / feminine / neuter)
number (singular / plural)
case (here: nominative)

The base adjective is hræddur (“afraid”). Its key forms:

masculine singular nominative: hræddur
feminine singular nominative: hrædd
neuter singular nominative: hrætt
neuter plural nominative: hrædd

Because ég here refers to a grammatically masculine speaker, the predicate adjective must be masculine singular nominative: hræddur.

A man would say: Ég er hræddur.
A woman would say: Ég er hrædd.
A little child could be referred to as neuter: Barnið er hrætt. (“The child is afraid.”)

So hræddur is correct for a male “I”. It will change if the speaker is grammatically feminine or neuter.

What exactly does lengur mean here, and why is it used with ekki?

Lengur literally means “longer” in a temporal sense, “for a longer time”.

With ekki, it forms the idiomatic combination:

ekki lengur = “no longer”, “not anymore”, “not any longer”

So:

Ég er ekki lengur hræddur = “I am no longer afraid / I am not afraid anymore.”

You could also move lengur:

Ég er ekki hræddur lengur. – also correct, same meaning.
(The first version sounds a bit more compact/natural, but both are fine.)

On its own, lengur (without ekki) normally means “still / yet / longer (in time)” in positive sentences:

Ég er enn lengur hér. – “I am here even longer.”

Why is ekki placed after er? Can I say Ég ekki er lengur hræddur?

You cannot say Ég ekki er lengur hræddur – that is ungrammatical.

In Icelandic main clauses, the finite verb must come in second position (verb‑second rule). The basic order is:

First element (often the subject): Ég
Finite verb: er
Then adverbs like ekki, lengur, etc.

So:

Ég er ekki lengur hræddur. – correct
Ég ekki er lengur hræddur. – incorrect (breaks verb‑second)

If you move a different element to the front, the verb still stays second:

Þegar ljósin eru kveikt, er ég ekki lengur hræddur.
(When the lights are lit, I am no longer afraid.)
– now þegar ljósin eru kveikt is first, er must still be second in the main clause.

What is the role of þegar here? Could I use þá instead?

Þegar is the subordinating conjunction “when”. It introduces a time clause:

þegar ljósin eru kveikt – “when the lights are lit / on”

This clause functions just like “when‑clauses” in English.

Þá is an adverb meaning “then” and is often used together with þegar:

Þegar ljósin eru kveikt, þá er ég ekki lengur hræddur.
Literally: “When the lights are lit, then I am no longer afraid.”

So:

Use þegar to mean “when (something happens / is true)”.
Þá is optional as a “then” in the main clause; you do not replace þegar with þá.

You cannot say:

*Ég er ekki lengur hræddur þá ljósin eru kveikt. – incorrect.
The “when” must be þegar.

Why is it ljósin and not just ljós? What is the function of -in?

Ljós is a neuter noun meaning “light” (as a lamp, light source). Its forms:

singular indefinite: ljós – “a light”
singular definite: ljósið – “the light”
plural indefinite: ljós – “lights”
plural definite: ljósin – “the lights”

The ending -in is the definite plural article for neuter nouns.

So:

ljósin eru kveikt literally = “the lights are lit / are on.”
If you said just ljós eru kveikt, that would be “lights are lit” (some lights, not specifically the lights).

Because English normally says “when the lights are on”, the Icelandic uses the definite plural ljósin.

What kind of form is kveikt, and why does it look the same for singular and plural neuter?

Kveikt here is the past participle of the verb kveikja (“to switch on, to light”). As a participle/adjective, it agrees with the noun it describes.

For kveiktur / kveikt (past participle of kveikja):

masculine singular nominative: kveiktur
feminine singular nominative: kveikt
neuter singular nominative: kveikt
masculine plural nominative: kveiktir
feminine plural nominative: kveiktar
neuter plural nominative: kveikt

Note that neuter plural = neuter singular in form: both are kveikt.

Since ljósin is neuter plural nominative, kveikt must also be neuter plural nominative – and that happens to look identical to neuter singular.

So:

Ljósin eru kveikt. – “The lights are lit / on.”
(neuter plural subject + neuter plural participle, which looks the same as neuter singular)

Why is the structure ljósin eru kveikt and not something like ljósin kveikja?

Ljósin eru kveikt is a stative passive construction:

ljósin – the lights (subject)
eru – are (form of vera)
kveikt – lit (past participle functioning as an adjective)

This describes the state of the lights: they are in a lit / on condition.

If you used kveikja as a normal verb, it would describe an action someone performs on the lights:

Ég kveiki á ljósunum. – “I turn on the lights.”
(kveiki is a finite verb, á ljósunum is “on the lights”.)

So:

ljósin eru kveikt – “the lights are lit / on” (state)
ég kveiki á ljósunum – “I switch on the lights” (action)

Could I say Ég er ekki lengur hræddur þegar það er kveikt á ljósunum instead? Does it mean the same?

Yes, that is also correct and natural:

Ég er ekki lengur hræddur þegar það er kveikt á ljósunum.

Literally: “I am no longer afraid when it is lit on the lights.”

Here:

það er kveikt á ljósunum = “the lights are on”
– literally: “it is lit on the lights”, where það is a dummy “it”, and á ljósunum = “on the lights”.

Both:

þegar ljósin eru kveikt
þegar það er kveikt á ljósunum

express essentially the same situation. The first is a bit shorter and more direct; the second is also very idiomatic in everyday speech when talking about lights being on.

Are there other natural word orders to say the same thing?

Yes. Icelandic word order is relatively flexible as long as the main verb remains in second position in main clauses. Some natural variants:

Moving lengur:
- Ég er ekki hræddur lengur þegar ljósin eru kveikt.
Putting the time clause first:
- Þegar ljósin eru kveikt, er ég ekki lengur hræddur.
- Þegar ljósin eru kveikt, þá er ég ekki lengur hræddur.
With the “kveikt á ljósunum” variant:
- Ég er ekki lengur hræddur þegar það er kveikt á ljósunum.
- Þegar það er kveikt á ljósunum, er ég ekki lengur hræddur.

All these are grammatical and mean the same thing; the choice mainly affects emphasis and style.