Rečenica je kratka.

Croatian has no articles like a/an or the.
The bare noun rečenica can mean a sentence or the sentence, depending on context.

So:

• Rečenica je kratka. = The sentence is short. or A sentence is short.
  Context decides whether it feels definite or indefinite; you don’t mark it with a separate word.

Rečenica is a feminine noun.

Common clues:

• Many feminine nouns end in -a in the nominative singular: žena, kuća, knjiga, rečenica.
• The dictionary form usually gives the gender, e.g. rečenica, -e (ž) where ž = ženski rod (feminine).

Because rečenica is feminine, any adjective describing it in the nominative singular must also be feminine singular nominative, like kratka.

The form of the adjective depends on the noun’s:

• gender
• number
• case

Here:

• rečenica = feminine, singular, nominative (it’s the subject)
• So kratak (short) must agree: kratka = feminine, singular, nominative.

Other examples with kratak:

• muški rod (m.): tekst je kratak – The text is short.
• srednji rod (n.): pismo je kratko – The letter is short.
• ženski rod (f.): rečenica je kratka – The sentence is short.

Je is the 3rd person singular present tense of the verb biti (to be).

Forms of biti (present):

• ja sam – I am
• ti si – you are (sg.)
• on/ona/ono je – he/she/it is
• mi smo – we are
• vi ste – you are (pl./formal)
• oni/one/ona su – they are

In Rečenica je kratka, je links the subject (Rečenica) with the adjective (kratka), just like is in English.

No, not in standard Croatian in the present tense. You normally must use je:

• ✔ Rečenica je kratka.
• ✖ Rečenica kratka. (sounds incomplete in standard language)

You may occasionally hear Rečenica kratka. in headlines, notes, or very telegraphic style, but that’s not normal full-sentence grammar.

Yes, Croatian word order is relatively flexible, and changes mostly affect emphasis, not grammatical correctness.

All of these are grammatically possible:

• Rečenica je kratka. – neutral, plain statement.
• Kratka je rečenica. – puts more emphasis on kratka (short).
• Rečenica kratka je. – possible, but sounds a bit marked/poetic.

For a beginner, it’s best to stick to the neutral order: [subject] + je + [adjective] → Rečenica je kratka.

Rečenica is in the nominative singular.

• It’s the subject of the sentence.
• The basic dictionary form of a noun is the nominative singular.

In a simple X je Y sentence, both X (subject) and the describing adjective Y are in the nominative:

• Rečenica je kratka. – rečenica (nom. sg.), kratka (nom. sg. fem.)

Yes. Adjectives must agree with the noun in:

• gender
• number
• case

Since rečenica is nominative, feminine, singular, the adjective kratak must take the nominative feminine singular form kratka.

Structure:

• [NOM, fem, sg] Rečenica
• [NOM, fem, sg] kratka

You need plural for the noun, verb, and adjective:

• Singular: Rečenica je kratka.
• Plural: Rečenice su kratke.

Changes:

• rečenica → rečenice (feminine nominative plural)
• je → su (3rd person plural of biti)
• kratka → kratke (feminine nominative plural of kratak)

You change the noun and make the adjective agree in gender:

• Masculine:

  • Tekst je kratak. – The text is short.
  • film, grad, zadatak etc. would also take kratak in nominative singular.

• Neuter:

  • Pismo je kratko. – The letter is short.
  • pitanje, ime, more etc. would take kratko.

So the pattern is:

• m. sg.: kratak
• f. sg.: kratka
• n. sg.: kratko

Yes, but the structure and focus are different:

• Rečenica je kratka.

  • Literally: The sentence is short.
  • Subject = Rečenica.
  • You’re making a statement about that sentence.

• To je kratka rečenica.

  • Literally: That is a short sentence.
  • Subject = To (that/this/it).
  • kratka rečenica is a noun phrase describing what to is.

Both can describe the same real-world situation, but grammatically and stylistically they’re different sentences.

No, rečenica is not a proper noun. It just gets a capital letter because it’s the first word of the sentence, just like in English.

In the middle of a sentence, it would be written with a lowercase r:

• Ova rečenica je kratka. – This sentence is short.

Approximate pronunciation:

• rečenica: [reh-CHEH-nee-tsa]

  • č is like ch in church.
  • The letter c at the end is pronounced like ts in cats.

• kratka: [KRAT-ka]

  • A rolled or tapped r.
  • All vowels are short and clear; no schwa sound.

Stress patterns can vary slightly regionally, but for learning: re-ČE-ni-ca, KRAT-ka is a good approximation.