Být — To Be (Introduction)

If you learn only one Czech verb properly, make it být ("to be"). It is the most frequent word in the language, and it pulls more grammatical weight than any other verb: it links subjects to descriptions, it announces that something exists, and — crucially — it is the engine inside the past tense, the future, the conditional, and the passive. Almost every sentence you build past the absolute beginner stage runs through být somewhere.

It is also, unsurprisingly, the most irregular verb in Czech. Its present-tense forms (jsem, jsi, je, jsme, jste, jsou) bear no resemblance to its infinitive být, and its future tense (budu, budeš, bude...) comes from a completely different root again. This is the same kind of suppletion you already know from English be / am / is / are / was / were — different-looking forms doing one verb's job. The good news is that because být is everywhere, you will internalise it fast.

This page is the conceptual overview: what být does and how it behaves in a sentence. For the full present paradigm drilled with its negatives, see the present tense of být; for every tense and mood in one place, see the být reference page.

The present tense at a glance

Here are the present forms, with the subject pronouns in parentheses because, as always in Czech, they are usually dropped.

The form seš for "you are" is (informal) Common Czech — extremely common in everyday speech, but you should write jsi.

Three jobs of být

1. The copula: linking a subject to a description

The first job is to connect a subject with a noun or adjective that describes it — exactly like English to be in "I am a student" or "she is tired." This is called the copula.

A genuinely Czech wrinkle hides here. When you name a profession or role, you often put the noun in the instrumental case rather than the nominative: Jsem učitelem alongside Jsem učitel (both "I'm a teacher"). The nominative states a plain identity; the instrumental frames it as a role you occupy. Beginners can safely use the nominative everywhere at first — see the instrumental as predicate for the full story.

2. The existential verb: saying something exists or is present

The second job is to assert that something exists or is located somewhere — the meaning English carries with "there is / there are."

This is where English speakers must retrain a habit. English needs a dummy subject — the empty word there — to make "there is a problem" grammatical. Czech has no such word. You simply use je (singular) or jsou (plural) and let word order do the work, typically putting the existing thing after the verb.

3. The auxiliary: the secret engine of other tenses

The third job is the one that makes být indispensable. It is the auxiliary verb — the helper — that builds the past tense, the future of imperfective verbs, the conditional, and the passive. You will study each of these later, but it is worth seeing now that the same little forms keep reappearing.

So the present forms (jsem, jsi...) become the past-tense helper, the future root (bud-) becomes the future helper, and a special set (bych, bys, by...) becomes the conditional helper. One verb, three machines.

The clitic nature of jsem, jsi, jsme, jste

Here is the single most important behavioural fact about být in the present, and the one that trips up nearly every learner. The forms jsem, jsi, jsme, jste are clitics: they are unstressed, they cannot start a sentence, and they lean on the word in front of them, sliding into the second position in the clause.

So you cannot translate "I am tired" word-for-word as Jsem unavený whenever there is something else at the front. If the sentence opens with another word, jsem moves to second place:

The forms je and jsou (3rd person) are heavier and more independent — they can carry stress and even begin a question — but jsem, jsi, jsme, jste are firmly second-position clitics. This rhythm is the heart of Czech word order, so it pays to feel it early. The present tense of být page drills exactly this.

Negation: ne- everywhere, but není in the singular

Czech negates a verb by gluing ne- to the front. With být this gives nejsem, nejsi, nejsme, nejste, nejsou — perfectly regular.

The exception is the third-person singular. You would expect neje, but the real negative is the fused, irregular form není ("is not"). This form is so common you will hear it within your first hour of Czech, so lock it in now: it is není, never neje.

Common Mistakes

Key Takeaways

• Být is the most frequent and most irregular Czech verb, with three jobs: copula, existential verb, and auxiliary.
• Present: jsem, jsi (colloq. seš), je, jsme, jste, jsou.
• Jsem, jsi, jsme, jste are second-position clitics — they cannot start a clause (Dnes jsem unavený).
• "There is / there are" = je / jsou with no word for "there."
• Negation is regular (nejsem, nejsi...) except the irregular 3sg není, never neje.
• Predicate nouns take the nominative, but roles and professions often take the instrumental (Jsem učitelem).