U nominativu kažemo "učiteljica", a u akuzativu "vidim učiteljicu".

Because Croatian changes noun endings depending on their role in the sentence.
Učiteljica is the nominative form, used for the basic dictionary form or for the subject of a sentence.

When the noun becomes a direct object after a verb like vidim (I see), it goes into the accusative.

So:

• učiteljica = nominative
• učiteljicu = accusative

For this feminine singular noun, the ending changes from -a to -u.

The nominative is mainly used for the subject of a sentence and for the basic form of a noun.

Examples:

• Učiteljica govori. = The teacher is speaking.
• Ovo je učiteljica. = This is a teacher / the teacher.

So učiteljica is the form you use when the teacher is the person doing the action, or when you are simply naming her.

The accusative is often used for the direct object: the person or thing directly affected by the action.

In vidim učiteljicu:

• vidim = I see
• učiteljicu = the teacher

So the teacher is the one being seen, not the one doing the seeing. That is why Croatian uses the accusative form učiteljicu.

Because vidjeti (to see) is a transitive verb, and in Croatian transitive verbs usually take a direct object in the accusative.

So:

• Vidim učiteljicu. = I see the teacher.
• Vidim psa. = I see the dog.
• Vidim knjigu. = I see the book.

This is very common in Croatian. If you learn a verb that takes a direct object, that object is often in the accusative.

It is singular.

• učiteljica = one female teacher, nominative singular
• učiteljicu = one female teacher, accusative singular

The plural forms would be different, for example:

• učiteljice = teachers / female teachers, nominative plural
• učiteljice = teachers / female teachers, accusative plural in many contexts

So in your sentence, both forms refer to one teacher.

Yes. Učiteljica is feminine and refers to a female teacher.

The masculine form is učitelj, which refers to a male teacher.

For example:

• učiteljica = female teacher
• učitelj = male teacher

This matters in Croatian because gender affects endings and agreement.

Many feminine singular nouns ending in -a do change to -u in the accusative, and učiteljica → učiteljicu follows that common pattern.

Examples:

• žena → ženu
• sestra → sestru
• knjiga → knjigu

However, Croatian has different noun classes, so not every feminine noun behaves exactly the same way. Still, for a beginner, feminine singular nouns ending in -a often take -u in the accusative is a very useful rule.

Because the whole word stem stays, and only the final ending changes.

The word is:

• učiteljic-a

In the accusative singular, that final -a becomes -u:

• učiteljic-u

So the result is učiteljicu.

It may look like a bigger change at first, but grammatically it is just -a → -u.

Yes. Ja vidim učiteljicu is grammatically correct.

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

So:

• vidim učiteljicu = I see the teacher
• ja vidim učiteljicu = I see the teacher

The version with ja may sound more emphatic, like I see the teacher.

Croatian normally does not use articles like English the or a/an.

So učiteljica or učiteljicu can mean:

• a teacher
• the teacher

The exact meaning depends on context.

That is why vidim učiteljicu can mean either I see a teacher or I see the teacher, depending on the situation.

No, Croatian word order is more flexible than English because case endings show grammatical roles.

The normal, neutral order is:

• Vidim učiteljicu.

But other orders are possible for emphasis, such as:

• Učiteljicu vidim.

Even if the order changes, the ending -u still tells you that učiteljicu is the direct object.

That said, beginners should usually start with the more neutral order: verb + object or subject + verb + object, depending on context.

Literally, u means in, so:

• u nominativu = in the nominative
• u akuzativu = in the accusative

This is a common way to talk about grammar in Croatian. It means when the noun is in that case.

So the sentence is explaining:

• in the nominative, we say učiteljica
• in the accusative, we say učiteljicu

Memorize the nominative singular first, because that is the usual dictionary form.

So you would learn:

• učiteljica

Then you learn its common case forms, such as:

• nominative: učiteljica
• accusative: učiteljicu

This is the normal way to build vocabulary in Croatian: learn the base form first, then learn how it changes.

The core meaning of the noun stays the same: it still means teacher.

What changes is the noun’s grammatical role in the sentence.

Compare:

• Učiteljica govori. = The teacher is speaking.
  Here, učiteljica is the subject.

• Vidim učiteljicu. = I see the teacher.
  Here, učiteljicu is the object.

So the case ending does not create a new word with a different basic meaning; it shows how that word functions in the sentence.

A simple learner-friendly guide:

• učiteljica ≈ oo-chee-teh-lyee-tsa
• učiteljicu ≈ oo-chee-teh-lyee-tsoo

A few helpful notes:

• u is like oo
• č sounds like ch in chocolate
• lj is a soft sound, roughly like lli in million for many English speakers
• c sounds like ts
• cu at the end sounds like tsoo

Exact pronunciation depends on accent, but this will get you close.

The main lesson is:

In Croatian, nouns change form depending on their function in the sentence.

This example shows a very common pattern:

• basic form / subject: učiteljica
• direct object after vidim: učiteljicu

So when you learn Croatian nouns, do not think only in terms of one fixed form. Always be ready for case changes, especially after verbs that take a direct object.