The Polish nominative case (naming and subject)

Co to jest? — To jest książka. Kto to jest? — To jest Anna.What is it? It's a book. Who is it? It's Anna.

Polish has seven cases, which means a noun changes its ending depending on its job in the sentence. The nominative (mianownik) is the case you start with: it is the plain dictionary form of a noun, the one you use to name a person or a thing and the one a subject takes. The other six cases come later; each has its own endings, and the nominative is the form you look up first.

Quick shortcut: when you name something (To jest …) or say who or what does the action, use the dictionary form: To jest kot. Kot śpi. When the noun is the thing the action is done to, it usually changes its ending: Czytam książkę.

Naming: To jest … and To są …

To say what something is, Polish uses to jest followed by the noun in the nominative. The noun stays in its dictionary form, and to never changes. For more than one thing, use to są with the plural nominative, which is covered in Plural of nouns in the nominative.

To jest dom. (This is a house.)
To jest szkoła. (This is a school.)
To jest okno. (This is a window.)
To są dzieci. (These are children.)

The two basic questions differ by what you ask about: kto for people and co for things. Both are followed by to jest and are answered with the nominative. More question words are in Question words.

Question	Answer
Co to jest? (What is it?)	To jest stół. · To jest woda. · To jest piwo.
Kto to jest? (Who is it?)	To jest Piotr. · To jest moja mama. · To jest nauczyciel.

The subject: who or what does it

The subject of a sentence is the person or thing the sentence is about, and it takes the nominative. You find it by asking kto? or co? before the verb, and the verb agrees with it (the gender of the noun matters in the past tense; see Polish noun gender).

Anna mieszka w Warszawie. (Anna lives in Warsaw.) — Kto mieszka w Warszawie? — Anna.
Kot śpi. (The cat is sleeping.) — Kto śpi? — Kot.
Książka leży na stole. (The book is on the table.) — Co leży na stole? — Książka.
Dzieci grają w piłkę. (The children are playing football.)

The personal pronouns ja, ty, on, ona, ono, my, wy, oni, one are also nominative forms, the ones used as the subject: see Personal pronouns. Polish often leaves the pronoun out when the verb ending already shows who is meant (Mieszkam w Krakowie.).

In many simple sentences the subject comes first, as in English. Polish word order is freer than English word order, though, so case endings often help show a noun's role, and verb agreement and context matter too.

The dictionary form is the nominative

A dictionary or a vocabulary list gives you a noun in the nominative singular, so that is the form to learn first: stół, książka, okno. As soon as the noun is used for something other than naming or being the subject, the ending usually changes. Compare:

Nominative (naming, subject)	Another case (here the accusative, the object of the verb)
To jest książka.	Czytam książkę. (I'm reading a book.)
To jest woda.	Piję wodę. (I'm drinking water.)
Książka jest ciekawa. (The book is interesting.)	Lubię tę książkę. (I like this book.)

You don't need to master the other forms yet. The first one to learn is the accusative: The accusative case with inanimate nouns. For now, notice that the dictionary form you learned is the one to use for naming and for the subject.

After być: nominative and instrumental

With to jest (and with to in a sentence like Piotr to nauczyciel), the noun stays in the nominative. But when a verb form of być (to be) is followed by a noun saying who someone is or what job they have, Polish normally puts that noun in the instrumental case instead:

To jest nauczyciel. (This is a teacher.) — nominative after to jest
Piotr to nauczyciel. (Piotr is a teacher.) — nominative after to
Piotr jest nauczycielem. (Piotr is a teacher.) — instrumental after jest
Jestem studentką. (I'm a student, said by a woman.) — instrumental

So in the nominative-only pattern, to jest is your friend. The instrumental after być is covered in The instrumental case: professions and z.

Common mistakes

❌ To jest książkę. → ✅ To jest książka. (naming uses the dictionary form)
❌ Czytam książka. → ✅ Czytam książkę. (the thing being read is not the subject, so it doesn't stay in the nominative)
❌ Co to jest? — To jest Piotr. → ✅ Kto to jest? — To jest Piotr. (use kto for a person)
❌ Jestem student. → ✅ Jestem studentem. (after a form of być, a noun that says who you are takes the instrumental)
❌ Piotra mieszka w Krakowie. → ✅ Piotr mieszka w Krakowie. (the subject takes the nominative)

Quick check

"____ to jest? — To jest kot." (Kto / Co)
"____ to jest? — To jest moja siostra." (Kto / Co)
"To jest ____." (szkoła / szkołę)
"____ mieszka w Gdańsku." (Anna / Annę)
Which word is the subject in Kot pije mleko? (Kot / mleko)

Show answers

Co (a thing) 2. Kto (a person) 3. szkoła (naming uses the nominative) 4. Anna (the subject uses the nominative) 5. Kot (it answers Kto pije mleko?)

Key takeaways

The nominative (mianownik) is the dictionary form of a noun, the one you learn first.
Use it to name things and people after To jest … / To są …, answering Co to jest? (things) and Kto to jest? (people).
Use it for the subject of a sentence, the answer to kto? or co? before the verb.
A noun that is not naming or the subject usually changes its ending: To jest książka, but Czytam książkę.
After a form of być, a noun saying who someone is or what job they have usually takes the instrumental: Jestem studentem; with to jest and to it stays nominative.