Tapet var stort.

Var is the past tense of å være (to be).

So:

• er = is / am / are
• var = was / were

In this sentence, Tapet var stort, var tells you the sentence is in the past.

Because tapet is a neuter noun in Norwegian: et tapet.

The adjective stor (big) changes form to match the noun:

• stor for common-gender singular
• stort for neuter singular
• store for plural

So with et tapet, you get:

• et stort tapet
• Tapet var stort

Even though stort comes after var, it still agrees with the noun.

You learn that from the noun’s dictionary form: et tapet.

In Norwegian, nouns have grammatical gender, and that affects articles and adjective endings. Since the article is et, the noun is neuter, which is why the adjective becomes stort.

A good habit is to learn new nouns together with their article:

• en bil
• ei bok
• et tapet

It is an adjective.

More specifically, it is a predicate adjective (also called a subject complement), because it describes the subject tapet after the verb var.

So the structure is:

• Tapet = subject
• var = verb
• stort = adjective describing the subject

It is not an adverb here.

That is a very reasonable question.

In many normal contexts, yes, you would often expect:

• et tapet = a wallpaper / a piece of wallpaper
• tapetet = the wallpaper

A bare noun like tapet can be used in some general or simplified contexts, especially in learning materials or when talking about something more like a substance/category.

So depending on the exact intended meaning, a more natural full sentence might be:

• Et tapet var stort
• Tapetet var stort

If this came from a beginner exercise, it may be simplified to highlight the grammar point var stort.

Here are the main forms:

• en stor bil = a big car
• et stort tapet = a big wallpaper / a big piece of wallpaper
• store biler = big cars

And in predicate position:

• Bilen er stor = The car is big
• Tapetet er stort = The wallpaper is big
• Bilene er store = The cars are big

So stort is specifically the neuter singular form.

No, this is the normal word order for a basic statement.

The sentence follows:

• subject + verb + complement

So:

• Tapet = subject
• var = verb
• stort = complement

This is very similar to English:

• The wallpaper was big

The most useful forms are:

• et tapet = an indefinite singular form
• tapetet = the definite singular form
• tapeter = indefinite plural
• tapetene = definite plural

So if you want to talk about one specific wallpaper, tapetet is often the form you would use.