Nominative in Predicates and Naming | Polish Grammar

The nominative (Polish mianownik) is the case of the subject, but it also turns up on the other side of być ("to be") in two specific situations: after the little word to ("this/that is"), and in naming, labels and citation. This matters enormously because Polish has two ways to say "X is Y" — one keeps the nominative, the other switches to the instrumental — and choosing wrong is one of the most common beginner errors. The good news: there's a clean, reliable rule, and it hinges on whether to is in the sentence. This page draws that boundary precisely and hands the instrumental side off to its own page.

The core split: is "to" present?

Polish builds "X is a Y" sentences two ways, and the case of the predicate noun depends on the construction:

Construction	Predicate noun case	Example
to (+ jest) + noun	NOMINATIVE	To jest lekarz. (This is a doctor.)
subject + być + noun	INSTRUMENTAL	On jest lekarzem. (He is a doctor.)

That's the whole secret in one table. When the sentence is anchored by to, the predicate noun stays nominative. When the sentence has a real personal subject (ja, ty, on, Anna…) linked by być to a role or category, the predicate noun goes into the instrumental (-em for masculine/neuter, -ą for feminine). English speakers miss this because English uses one structure ("He is a doctor") and one form of the noun for both jobs.

To jest mój nowy nauczyciel.

This is my new teacher.

On jest nauczycielem w liceum.

He is a teacher at a secondary school.

Same person, same profession, two grammars: nauczyciel (nominative, with to) versus nauczycielem (instrumental, with on jest). Watch the diacritic-free but ending-bearing instrumental form -em.

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The decision rule fits on a sticky note: if you can see (or insert) "to", keep the nominative; if the subject is a person/thing and there's no "to", use the instrumental. This single test resolves the great majority of "X is Y" sentences and is, oddly, under-taught in beginner courses — many learners reach B1 still guessing.

The "to" side: identifying and pointing out

The to construction is how Polish says "this is / that is / these are" — pointing something out, identifying it, defining it. The predicate noun after it is plain nominative, exactly as it would appear in a dictionary or as a subject. The verb jest/są is optional and often dropped.

To moja siostra Ania.

This is my sister Ania.

To jest dom, w którym dorastałem.

This is the house I grew up in.

Co to jest? — To słownik.

What is this? — It's a dictionary.

Notice that to here is invariant — it does not agree with the noun in gender or number. You say to moja siostra (feminine noun), to mój brat (masculine noun), to są moje dzieci (plural) — to stays to throughout, functioning like a fixed "this is / these are." For the construction in depth, see the to jest construction and to as 'this is'.

A useful consequence: because the predicate is nominative, you can chain definitions naturally — Warszawa to stolica Polski ("Warsaw is the capital of Poland"), where to links two nominative nouns like an equals sign. This noun + to + noun pattern (definitional, encyclopedic) always keeps both sides nominative.

Wisła to najdłuższa rzeka w Polsce.

The Vistula is the longest river in Poland.

The instrumental side: roles, professions, identities

When there's a genuine subject and you're assigning it to a category, profession, role or identity via być, Polish uses the instrumental for the predicate noun. This is the standard pattern for "I am a (teacher/student/Pole/engineer)."

Jestem nauczycielem, a moja żona jest lekarką.

I'm a teacher, and my wife is a doctor.

Czy pan jest Polakiem?

Are you Polish? (lit. Are you a Pole?)

Chcę zostać inżynierem.

I want to become an engineer.

The instrumental endings: masculine/neuter -em (nauczycielem, studentem, Polakiem, dzieckiem), feminine -ą (lekarką, studentką, Polką) — note the feminine -ą carries the ogonek. After być and especially after zostać ("to become"), this instrumental predicate is obligatory. This whole side has its own dedicated page — the instrumental predicate — which is where you should drill the forms. Here we only mark the boundary so you know which page you need.

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Why the instrumental at all? The instrumental predicate frames the noun as a role you occupy rather than a permanent equation — "I function as a teacher." That's why temporary or assigned states (professions, nationalities-as-roles, "being the chairman this year") take it, and why zostać ("become") forces it. The to + nominative pattern, by contrast, is pure identification: "this thing = that thing." See the być + instrumental mistakes page.

A direct contrast you'll use constantly

Hold these two side by side until the difference is automatic:

To jest lekarz.

This is a doctor. (pointing someone out — nominative)

On jest lekarzem.

He is a doctor. (stating his profession — instrumental)

Both are perfectly correct Polish; they're not interchangeable stylistic variants but answers to different questions. To jest lekarz answers "who/what is this?" (you're picking the doctor out of a group). On jest lekarzem answers "what does he do? / what is he?" (you're classifying him). You can even combine them: To jest pan Kowalski. On jest lekarzem. ("This is Mr Kowalski. He's a doctor.")

Naming, titles, labels and citation: nominative

Beyond to, the nominative is the case of bare naming — when a word stands as a label rather than playing a grammatical role in a sentence. This covers:

Dictionary / citation form. When you talk about a word or quote it as a form, it's nominative: Jak jest "stół" w liczbie mnogiej? ("What is 'stół' in the plural?").
Titles and headings. Book titles, signs, captions: „Pan Tadeusz", Wyjście ("Exit"), Kasa ("Cashier").
Lists and labels. A shopping list reads chleb, masło, mleko — all nominative, none of them objects of a verb.
Answering "what's it called?" with a name in isolation.

Jak się nazywa ta ulica? — Marszałkowska.

What's this street called? — Marszałkowska.

Na liście mam: chleb, ser, jajka i pomidory.

On the list I've got: bread, cheese, eggs and tomatoes.

There's one subtlety with nazywać się ("to be called/named"). When the name is treated as a quoted label, it's nominative: Ten film nazywa się „Rejs". But when you say what someone's surname is, the instrumental can appear in more formal framings; in everyday speech the nominative label is the norm: Nazywam się Kowalski ("My name is / I'm called Kowalski" — nominative). See nazywać się.

Mój pies nazywa się Burek.

My dog is called Burek.

Edge cases and honest caveats

A few honest notes so you're not blindsided:

Adjective predicates take the nominative, not the instrumental. "He is tall/tired/Polish-as-adjective" uses a plain nominative adjective: On jest wysoki, Jestem zmęczony, Ona jest miła. The instrumental rule is for predicate nouns, not adjectives. (Jestem Polakiem — noun, instrumental — but jestem polski would be odd; nationality as a noun-role takes the instrumental.)
"To jest" + instrumental is wrong. Don't blend the two: it's To jest lekarz (nom.), never To jest lekarzem.
Pronoun + to. You can say On to mój brat ("He's my brother") — to still triggers the nominative on the predicate even with a pronoun subject, because the to-anchor is present. This is a real, common pattern, slightly more emphatic than On jest moim bratem.

On to dobry człowiek, możesz mu zaufać.

He's a good man, you can trust him.

Common Mistakes

❌ To jest lekarzem.

Incorrect — with 'to' the predicate noun stays nominative: lekarz.

✅ To jest lekarz.

This is a doctor.

❌ On jest nauczyciel.

Incorrect — a personal subject + być takes the instrumental: nauczycielem.

✅ On jest nauczycielem.

He is a teacher.

❌ Jestem student.

Incorrect — profession after być is instrumental: studentem.

✅ Jestem studentem.

I'm a student.

❌ Ona jest lekarzem.

Incorrect — the feminine instrumental is lekarką (-ą), not the masculine -em.

✅ Ona jest lekarką.

She is a doctor.

❌ Jestem zmęczonym.

Incorrect — predicate adjectives take the nominative, not the instrumental: zmęczony.

✅ Jestem zmęczony.

I'm tired. (male speaker)

Key Takeaways

"X is Y" splits by construction: to (+ jest) + noun → nominative; subject + być + noun → instrumental.
The test: see or insert "to" → keep the nominative; personal subject, no "to" → instrumental.
to is invariant ("this is / these are") and links two nominatives in definitions (Warszawa to stolica Polski).
Predicate adjectives stay nominative (jestem zmęczony); only predicate nouns take the instrumental.
Naming, titles, labels, lists and citation forms are all nominative.

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