Learn Hardcore Icelandic: Hnífurinn er beittur.

hnífur means “knife” (a masculine noun). The suffix -inn is the definite article for masculine singular, so hnífurinn literally means “the knife.”

What case is hnífurinn in, and why?

It’s in the nominative case because it’s the subject of the sentence. In Icelandic, subjects take the nominative.

What is er here?

er is the 3rd-person singular present tense of að vera (“to be”). It’s the copula linking hnífurinn (the subject) to beittur (the predicate adjective).

Why does beittur end in -ur?

Adjectives in Icelandic agree in gender, number, and case with the noun they describe. beittur is in the strong (predicative) form for masculine nominative singular, hence the -ur ending.

Why can’t we just say beitt without the -ur?

beitt is the neuter nominative singular form. Since hnífurinn is masculine, the correct form is beittur, not beitt.

How would you say “The knife is not sharp”?

Insert the negator ekki after the verb:
Hnífurinn er ekki beittur.

How do you turn it into a question: “Is the knife sharp?”

Use inversion (V2 word order):
Er hnífurinn beittur?

How do you say “The knives are sharp”?

Use the plural forms:
hnífarnir (masc. nom. pl. definite) + eru (3rd-person pl. of vera) + beittir (masc. nom. pl. adjective) →
Hnífarnir eru beittir.

Can you give a pronunciation guide for Hnífurinn er beittur?

Rough IPA: [ˈn̥iːvʏronː ɛr ˈpeihtʏr].

The hn is a voiceless n̥.
tt in beittur is a long [ht].

Is beittur a past participle or an adjective here?

It originates from the past participle of að beita (“to sharpen”), but in this sentence it functions purely as a predicate adjective meaning “sharp.”