Na kraju sata profesorica traži da u jednoj rečenici napišemo značenje novog glagola i jedan antonim za pridjev koji učimo.

Not in this sentence. Although tražiti can mean to look for / to search for, here it means to ask for, to require, or to expect.

So profesorica traži da... means something like:

• the teacher asks that...
• the teacher requires us to...
• the teacher wants us to...

In classroom language, this is very natural.

Na kraju sata means at the end of the class/lesson.

Here:

• kraj = end
• na kraju = at the end
• sata is genitive singular of sat

The pattern is:

• na kraju + genitive

So:

• na kraju dana = at the end of the day
• na kraju filma = at the end of the film
• na kraju sata = at the end of the class

Even though sat often means clock or hour, in school context it can also mean class period / lesson.

Profesorica is the feminine form, so it means female teacher/professor.

• profesor = male professor/teacher
• profesorica = female professor/teacher

Croatian usually marks grammatical gender clearly in nouns referring to people, so if the teacher is a woman, profesorica is the natural choice.

Because Croatian very often uses da + present tense after verbs of asking, wanting, requiring, suggesting, etc., especially when the subject of the second verb is different from the subject of the first verb.

Here:

• profesorica traži = the teacher asks
• da napišemo = that we write

The teacher is the subject of traži, but we are the subject of napišemo, so a da-clause is the normal structure.

This is very common in Croatian:

• Želim da dođeš. = I want you to come.
• Traže da čekamo. = They ask us to wait.

English often uses an infinitive in similar situations, but Croatian usually does not.

Because napisati is the perfective verb, while pisati is imperfective.

• pisati = to write, to be writing, to write in general
• napisati = to write down, to complete writing

In this sentence, the teacher wants one completed action: that we write one sentence and finish it. That is why napišemo is used.

So:

• da pišemo would suggest ongoing or repeated writing
• da napišemo means that we write and complete it

This is a very common aspect choice in Croatian.

Because Croatian often drops subject pronouns when they are already clear from the verb ending.

Napišemo has the ending -mo, which tells you it is 1st person plural:

• I / we do not need to be stated separately
• napišemo already means we write / we should write

You could say da mi napišemo, but it would usually sound unnecessary unless you want emphasis.

That is locative singular.

After u, Croatian uses:

• accusative for movement into something
• locative for being in something

Here the meaning is in one sentence, not into one sentence, so the locative is used:

• u jednoj rečenici

Breakdown:

• jedna rečenica = one sentence
• u jednoj rečenici = in one sentence

Both words change because they agree in:

• gender: feminine
• number: singular
• case: locative

Because jednoj is the locative singular feminine form, while jednu is accusative singular feminine.

Compare:

• u jednoj rečenici = in one sentence → locative
• pišem jednu rečenicu = I am writing one sentence → accusative

So the difference comes from the role of the phrase in the sentence.

Novog glagola is genitive singular.

The noun značenje means meaning, and Croatian often uses the genitive to express meaning of something.

So:

• značenje glagola = the meaning of the verb
• značenje novog glagola = the meaning of the new verb

Breakdown:

• glagol = verb
• novi glagol = a new verb
• novog glagola = of a new verb

The adjective novog agrees with glagola in case, gender, and number.

Because antonim is a masculine inanimate noun, and in Croatian the accusative singular of masculine inanimate nouns is the same as the nominative singular.

So:

• nominative: jedan antonim
• accusative: jedan antonim

That is why this direct object looks like the dictionary form.

Compare that with a masculine animate noun:

• vidim jednog studenta = I see one student

So the form changes for animate nouns, but not for masculine inanimate nouns like antonim.

Here za means for.

So jedan antonim za pridjev means an antonym for the adjective.

This is a natural way in Croatian to show what the antonym corresponds to:

• sinonim za riječ = a synonym for a word
• antonim za pridjev = an antonym for an adjective

After za, the noun goes into the accusative:

• pridjev is masculine inanimate singular
• accusative singular = pridjev

So the form does not visibly change.

Koji here refers back to pridjev.

In the clause pridjev koji učimo, the meaning is the adjective that we are learning.

Grammatically, koji is the object of učimo, so it is in the accusative singular masculine. But because pridjev is masculine inanimate, the accusative form looks the same as the nominative:

• nominative masculine inanimate singular: koji
• accusative masculine inanimate singular: koji

So even though it looks like nominative, in this sentence it functions as the accusative object.

Because učimo describes an ongoing learning process: the adjective we are learning.

The verb učiti is imperfective, and that fits the idea well:

• učiti = to learn, to study, to be learning
• naučiti = to learn completely, to master, to memorize

In the relative clause, the point is not that we have already mastered the adjective, but that it is the adjective currently being studied in class. So učimo is the natural choice.

Yes, Croatian word order is fairly flexible, but this version is natural and clear.

The sentence starts with Na kraju sata, which sets the time context first:

• At the end of class...

Then comes the subject:

• profesorica

Then the main verb:

• traži

Then the da-clause:

• da ... napišemo ...

This ordering sounds normal in classroom narration. Croatian can move parts around for emphasis, but not every alternative sounds equally natural. The given version is a good neutral word order.

It is mostly neutral standard Croatian.

It sounds like something you might read in a textbook or hear in a classroom description. Nothing in it is slangy or unusually formal.

A teacher could naturally say something similar in real life, and a textbook could also use it as an example sentence.