Vi ventet et døgn.

Døgn means a full 24-hour period: day and night together.

That is different from dag, which often means day in the sense of:

• the daytime,
• a calendar day,
• or one day in a more general sense.

So Vi ventet et døgn specifically means we waited for 24 hours.
If you used dag, it might sound less precise.

Because døgn is a neuter noun in Norwegian. Neuter nouns take et in the indefinite singular.

So:

• et døgn = a 24-hour period

This is just something you have to learn with the noun: Norwegian nouns can be masculine, feminine, or neuter.

In Norwegian, a duration of time can often be expressed directly, without a preposition.

So:

• Vi ventet et døgn = We waited a day / for a day / for 24 hours

This works much like English in sentences such as:

• We waited an hour
• She slept all day

The time expression et døgn functions as a duration phrase.

Ventet is the past tense of vente (to wait).

So:

• vente = to wait
• venter = wait / is waiting
• ventet = waited
• har ventet = have/has waited

In this sentence, Vi ventet et døgn is a simple past statement: We waited for 24 hours.

Usually, yes, the final -t is pronounced, though exactly how clearly it is heard can vary by speaker and dialect.

A learner should aim to pronounce:

• ventet roughly as VEN-te(t)

The ending is not strongly stressed, but it is still part of the word.

This is the normal Norwegian main-clause order:

• Vi = subject
• ventet = verb
• et døgn = object/time duration expression

So the pattern is basically: Subject + Verb + Time expression

This is very similar to English:

• We waited a day

Yes. That would also be correct, but it means something slightly different.

• Vi ventet et døgn = We waited for 24 hours
  This presents the waiting as a completed event in the past.

• Vi har ventet et døgn = We have waited for 24 hours
  This connects the waiting more directly to the present situation.

So both are possible, but they are used in different contexts.

Yes, you could, but it is not exactly the same.

• Vi ventet en dag = We waited a day
• Vi ventet et døgn = We waited a full 24-hour period

En dag can sometimes sound more general or less exact.
Et døgn sounds more precise and often more natural when you really mean 24 hours.

Yes, it is quite common, especially when talking about:

• lengths of time,
• weather reports,
• hospital stays,
• travel delays,
• opening hours,
• or anything measured in 24-hour units.

For example:

• et døgn = 24 hours
• to døgn = two 24-hour periods

So it is a useful everyday word, not a rare or overly formal one.

The plural is usually the same form:

• et døgn = one 24-hour period
• flere døgn = several 24-hour periods

Examples:

• Vi ventet to døgn. = We waited two days / 48 hours.
• Han sov nesten et helt døgn. = He slept for almost a whole day.

So døgn is one of those nouns whose plural form does not change.

Yes. It can combine with words that make the duration more specific, for example:

• et helt døgn = a whole 24 hours
• ett døgn = one 24-hour period, with extra emphasis on the number
• i et døgn = for 24 hours
• over et døgn = over 24 hours

So while Vi ventet et døgn is perfectly natural, you may also see døgn in slightly longer time expressions.

Because Vi is simply the Norwegian subject pronoun meaning we.

The sentence breaks down as:

• Vi = we
• ventet = waited
• et døgn = a 24-hour period / for 24 hours

So Vi ventet et døgn is a very straightforward Norwegian sentence: We waited for 24 hours.