Spelling Long u: ú versus ů | Czech Grammar

Czech has two ways to spell the long vowel [uː] — the drawn-out oo of English moon — and they sound absolutely identical. One is ú (u s čárkou, "u with an acute"); the other is ů (u s kroužkem, "u with a little ring"). Your ears will never tell them apart, so this is one of the rare corners of otherwise phonetic Czech spelling where you simply have to know a rule. The good news: the rule is almost purely positional — it depends only on where in the word the long u sits — and once you have it, you get it right every time.

The one rule that does almost all the work

Spelling	Where	Examples
ú (acute)	at the start of a word, or at the start of a root after a prefix	úkol, únor, účet, trojúhelník, neúnavný
ů (ring)	in the middle or at the end of a word	dům, stůl, kůň, můžu, domů

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ú knocks on the front door; ů lives inside the house. If the long u is the first thing in the word (or the first thing in a root that a prefix has been glued onto), write ú. Anywhere else — the middle or the very end — write ů.

Why ů never starts a word — the historical reason

This isn't an arbitrary decision by some committee. The ring on ů is a fossil. Centuries ago the sound was a falling diphthong uo: old Czech said kuoň, duom, stuol. Over time the uo contracted into a plain long [uː], but the spelling kept a reminder of the vanished o by perching a little ring on top — kůň, dům, stůl. Because that uo → ů development only ever happened inside words (it came out of older vowels that lived in the middle of a stem), ů can never appear at the start of a word. The acute ú, by contrast, marks a long u that was always just a long u, and that's the sound you typically meet at the front of a word. So the rule is really history wearing a costume: front means "always long u" (ú), inside means "used to be uo" (ů).

ú — at the front

Word-initial long u is always ú. Czech has a large family of words built on the prefix ú- and on roots that simply begin with a long u.

Tenhle úkol mi vůbec nejde, pomůžeš mi s ním?

I can't get this assignment to work at all, will you help me with it? (úkol opens with ú; vůbec and pomůžeš carry ů inside)

V únoru jsem byl pořád unavený a ta zimní únava byla k nevydržení.

In February I was constantly tired, and that winter fatigue was unbearable. (únor, únava — both start with ú)

Můžeš mi prosím poslat ten účet e-mailem?

Can you please send me that invoice by e-mail? (můžeš = ů inside; účet = ú at the front)

Měla na tváři úsměv od ucha k uchu.

She had a smile from ear to ear. (úsměv begins with ú)

The same holds after a prefix, because gluing a prefix onto the front doesn't change where the root begins — the root still "starts," even though it's no longer the first letter of the whole word. A root that takes ú on its own keeps that ú after a prefix.

Je to neúnavný pracant, nikdy si neodpočine.

He's a tireless worker, he never takes a rest. (ne + únavný keeps its ú)

Narýsuj prosím rovnostranný trojúhelník.

Please draw an equilateral triangle. (troj + úhel → trojúhelník keeps the ú)

Šéf nás zase na celý týden zaúkoloval.

The boss loaded us up with tasks again for the whole week. (za + úkolovat → zaúkoloval keeps the ú)

ů — in the middle and at the end

Everywhere else — the moment the long u is not at the start of a word or root — you write ů. This covers an enormous number of the most everyday words in the language, including final position.

Náš dům stojí hned vedle školy.

Our house is right next to the school. (dům = ů in the middle)

Postav ten stůl ke zdi, ať máme víc místa.

Put that table against the wall so we have more room. (stůl)

Dej pozor, ten kůň občas kouše.

Watch out, that horse bites sometimes. (kůň)

Podej mi sůl, prosím — a z kuchyně se line nádherná vůně.

Pass me the salt, please — and a wonderful smell is wafting from the kitchen. (sůl, vůně)

Už je pozdě, pojďme domů.

It's late, let's go home. (domů ends in ů — final position)

Loanwords are the exception: they keep ú inside

There's one clean exception, and it's worth memorising because it overrides the position rule. Words borrowed from other languages keep ú even in the middle or at the end — they never had a uo diphthong, so they never earned a ring. If a word feels foreign and has a long u sound mid-word, your default should be ú.

O víkendu jsme byli na krásné túře v Krkonoších.

At the weekend we went on a lovely hike in the Giant Mountains. (túra keeps ú mid-word — a loanword)

Manželka má objednanou manikúru a po nemoci jí doktor předepsal lázeňskou kúru.

My wife has a manicure booked, and after her illness the doctor prescribed a spa treatment. (manikúra, kúra — both loanwords keep ú)

Fúze těch dvou firem se táhla skoro celý rok.

The merger of those two companies dragged on for almost a year. (fúze keeps ú)

Děti si na zahradě postavily ze sněhu iglú.

The children built an igloo out of snow in the garden. (iglú — a loanword keeps ú even at the very end)

Note that last one: a native word ending in long u takes ů (domů, dolů), but a borrowed one ending in long u takes ú (iglú, ragú, menú). The ending tells you almost nothing on its own — you have to know whether the word is home-grown or imported.

One word, both spellings

Because the rule is positional, a single word can legitimately show both letters at once. Take úkol (a task). Its genitive plural is úkolů: it starts with ú because that's the front of the word, and it ends with ů because that's the end. Identical sound, two spellings, one word — and both are correct.

Na zítřek máme hrozně moc úkolů.

We have an awful lot of homework for tomorrow. (úkolů: ú at the front, ů at the end)

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When you're unsure, picture the spoken word and ask one question: is this long u the very first sound, or the start of a root after a prefix? Yes → ú. No (and not a loanword) → ů. That single question resolves nearly every case.

A note on register

The spelling rule itself is fixed across all registers — there's no "casual" way to write these letters. But you'll meet some of the example words in different styles. Můžu (I can) is the everyday (informal) form; the (formal) / (literary) equivalent is mohu, which keeps the same ů. Likewise domů (homewards) is neutral everywhere. The takeaway: ú and ů are spelled by position, not by how formal you're being.

Common Mistakes

English speakers don't have these letters at all, so the usual error is to guess — or to pick one symbol and use it everywhere. Here are the four traps that catch nearly everyone.

❌ Náš dúm je velký.

Incorrect — the long u is in the middle, so it must be ů.

✅ Náš dům je velký.

Our house is big.

❌ Tohle je tvůj ůkol.

Incorrect — the long u starts the word, so it must be ú.

✅ Tohle je tvůj úkol.

This is your task. (ů inside tvůj, ú at the start of úkol)

❌ Pojďme už domú.

Incorrect — final long u in a native word is ů, not ú.

✅ Pojďme už domů.

Let's go home now.

❌ Byli jsme na túře, ale píšu to jako tůra.

Incorrect — túra is a loanword and keeps ú even though the u is inside.

✅ Byli jsme na túře.

We went on a hike. (loanword keeps ú)

❌ Je to neůnavný člověk.

Incorrect — the root únav- starts after the prefix ne-, so it keeps ú.

✅ Je to neúnavný člověk.

He's a tireless person.

Key Takeaways

Long u is spelled ú at the start of a word or root (after a prefix), and ů in the middle or at the end. Same sound, different letter.
ů carries a frozen reminder of an old uo diphthong, which is exactly why it can never begin a word.
Loanwords keep ú everywhere (túra, kúra, manikúra, fúze, iglú) — they never had the diphthong, so they never get a ring.
One word can show both: úkolů.
The two letters are identical in pronunciation; the choice is spelling-only.

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