Die Nuss ist hart.

The nut is hard.

Breakdown of Die Nuss ist hart.

• sein: to be
• hart: hard
• die Nuss: the nut

Questions & Answers about Die Nuss ist hart.

Why is it die Nuss and not der or das?

Because Nuss is a feminine noun in German: die Nuss (singular), die Nüsse (plural). Noun gender is mostly something you have to learn with the word, although some endings give hints—this one doesn’t reliably.

What does hart mean here, and can it mean different things?

Hart most commonly means hard in the physical sense (not soft). Depending on context, it can also mean tough/strict/harsh (e.g., harte Regeln = strict rules), but in Die Nuss ist hart it’s the literal physical meaning.

Why is the adjective just hart and not changed (like harte)?

Because after the verb sein (to be), adjectives are used in the predicative position and do not take endings:

• Die Nuss ist hart. (predicative → no ending)

Adjective endings appear when the adjective is before the noun (attributive):

• die harte Nuss (attributive → ending -e)

Is ist always the right word for is?

For sein in the present tense, yes: ist = (he/she/it) is.
Conjugation of sein (present):

• ich bin
• du bist
• er/sie/es ist
• wir sind
• ihr seid
• sie/Sie sind

So Die Nuss ist hart matches third-person singular.

What case is die Nuss in?

It’s in the nominative case because it is the subject of the sentence. With sein, the thing described is the subject, and the adjective describes it.

Could I also say Eine Nuss ist hart? What changes?

Yes.

• Die Nuss ist hart. = the nut (a specific nut, or nuts in general depending on context)
• Eine Nuss ist hart. = a nut (one unspecific example)

Only the article changes: die → eine.

Does this sentence imply “nuts are hard” in general, or “this particular nut is hard”?

It depends on context. German, like English, can use the + singular for a general statement in some contexts, but usually:

• Die Nuss ist hart. often sounds like a specific nut you’re talking about. For a clearer general statement, you might use:
• Nüsse sind hart. (Nuts are hard.)

What’s the plural form, and how would the sentence look in plural?

Plural:

• die Nüsse = the nuts
  Sentence:
• Die Nüsse sind hart. (The nuts are hard.)

Note that ist changes to sind, but hart still stays unchanged (still predicative).

How is Nuss pronounced, especially the u?

Nuss is pronounced roughly like nooss with a short u sound: /nʊs/.
It’s similar to the vowel in English put (in many accents), not like goose.

What’s the difference between hart and härter/härteste?

Those are comparison forms:

• hart = hard
• härter = harder
• am härtesten = (the) hardest (used with am in predicative comparisons)

Examples:

• Diese Nuss ist härter. (This nut is harder.)
• Diese Nuss ist am härtesten. (This nut is the hardest.)

Could hart be used as an adverb here?

In this sentence, hart is an adjective describing the subject via sein.
German often uses the same form for adverbs and predicative adjectives (no -ly equivalent), but here the function is clearly adjectival: “The nut is hard.”

Is word order fixed? Could I say Hart ist die Nuss?

Yes, German allows flexibility. Die Nuss ist hart is the neutral order.
Hart ist die Nuss is possible but emphasizes hart (like “Hard is the nut”). It’s more stylistic and less common in everyday speech unless you’re contrasting it with something.

Is there a common idiomatic use of eine harte Nuss?

Yes: eine harte Nuss (sein) means a tough nut (to crack), i.e., a difficult problem or person.
Examples:

• Das ist eine harte Nuss. (That’s a tough nut.)
• Er ist eine harte Nuss. (He’s a tough one / hard to deal with.)