Learn Hardcore Icelandic: Veggurinn er hvítur.

-inn is the definite article in Icelandic for masculine singular nominative. The base form is veggur (‘a wall’). Adding -inn turns it into veggurinn (‘the wall’).

How would you say “a wall is white” instead of “the wall is white”?

Use the indefinite noun veggur (no -inn) with the same adjective:
Veggur er hvítur.
This literally means “A wall is white.”

Why is the adjective hvítur used here, and how does it agree with veggurinn?

Adjectives in Icelandic must match the noun they describe in gender, number, and case. Veggurinn is masculine, singular, nominative, so the adjective takes the masculine singular nominative strong form hvítur.

Shouldn’t the adjective hvítur take a definite ending (like hvíturinn) because veggurinn is definite?

No. In predicate position (after the verb er), adjectives always use the strong declension and do not take the definite suffix. You never say hvíturinn here—hvítur remains unchanged.

What grammatical case is veggurinn in, and why?

It’s in the nominative case, which is used for the subject of a sentence. Since veggurinn is the subject of er (‘is’), it stays in the nominative singular.

How is the double gg in veggurinn pronounced?

In Icelandic, gg between vowels represents a long [kː] sound. Thus veggurinn is pronounced approximately [ˈvɛkːʏrɪn] with a prolonged k.

Where is the stress in words like veggurinn and hvítur?

Icelandic words are almost always stressed on the first syllable. So you say VEG-gur-inn and HVI-tur (emphasis on VEG and HVI).