English "both" is one frozen word that sits in front of a noun — "both brothers," "both windows" — and never changes. Czech oba / obě does the same determiner job, but it inflects: it splits by gender in the nominative (oba for masculine, obě for feminine and neuter) and keeps a special set of oblique forms, obou and oběma, that preserve fossilised dual endings from an older stage of the language. This page treats oba/obě as a determiner — how it sits before a noun and quantifies it — and points you to the full Numbers treatment for the complete declension and the dual relics.
The gender split before a noun
Placed in front of a noun in the subject or object slot, oba/obě agrees with that noun's gender, exactly mirroring dva / dvě:
| Gender of noun | Form | Example |
|---|---|---|
| masculine (animate & inanimate) | oba | oba bratři, oba domy |
| feminine | obě | obě sestry |
| neuter | obě | obě auta |
The noun stands in the nominative plural — not the genitive. This is the key difference from "five and up," which would force a genitive. Oba patterns with the low numbers dva/tři/čtyři, keeping the plain plural.
Oba bratři pracují v nemocnici.
Both brothers work at the hospital.
Obě sestry se přistěhovaly do Brna.
Both sisters moved to Brno.
Obě auta jsou zaparkovaná před domem.
Both cars are parked in front of the house.
Notice obě covers both sestry (feminine) and auta (neuter) — one form for two genders, just as dvě does. Only the masculine gets the distinct oba.
Verb agreement: plural
Because oba/obě points at two real entities, it takes a plural verb — unlike the genitive quantifiers (mnoho, několik), which go singular neuter. And with masculine animate nouns the past-tense participle takes the animate -i ending, exactly as with any masculine-animate plural subject.
Oba kamarádi přišli včas.
Both friends arrived on time. (přišli — masculine animate plural)
Obě holky se smály.
Both girls were laughing. (smály — feminine plural)
Obě okna se rozbila.
Both windows broke. (rozbila — neuter plural)
Oblique cases as a determiner: obou and oběma
When the oba-phrase itself lands in an oblique case, the determiner declines with the noun. There are only two oblique forms to learn, and they cover several cases each:
| Case(s) | Form | Example |
|---|---|---|
| genitive & locative | obou | z obou stran (from both sides) |
| dative & instrumental | oběma | s oběma rodiči (with both parents) |
Slyšel jsem to z obou stran.
I heard it from both sides. (genitive: obou)
Domluvil jsem se s oběma rodiči.
I arranged it with both parents. (instrumental: oběma)
Věnoval pozornost oběma návrhům.
He paid attention to both proposals. (dative: oběma)
oba vs. dva vs. všichni: which determiner?
This is the choice English speakers have to make consciously, because English "both / two / all" map onto it only loosely:
- oba/obě — both, i.e. the two specific ones already in view. Presupposes a known pair.
- dva/dvě — two, a bare count, no presupposition of "the specific pair."
- všichni/všechny — all, the totality of a larger set (three or more), covered on the all / whole page.
Mám dva bratry a oba žijí v zahraničí.
I have two brothers and both of them live abroad. (dva = introduces the count; oba = 'the two of them')
Pozvala všechny kolegy, ne jen ty dva.
She invited all the colleagues, not just those two. (všechny = the whole set)
The progression in that first sentence is telling: you introduce a pair with dva ("I have two brothers"), then refer back to the known pair with oba ("both of them"). Oba is anaphoric — it points to a duo you've already established.
The dual relic: oběma rukama
Czech long ago lost its dual number, but a few fossils survive with body parts that naturally come in pairs — hands, eyes, ears, legs — and oba/obě is one of the words that keeps the old dual instrumental. So "with both hands" is oběma rukama (not rukami), "with both eyes" oběma očima, "with both ears" oběma ušima.
Držela to oběma rukama.
She held it with both hands. (rukama — dual relic)
Poslouchal oběma ušima.
He listened with both ears. (ušima — dual relic)
These are treated more fully, alongside the complete declension, on the Numbers 'both' page — as a determiner you mainly need to recognise them as set phrases.
Common Mistakes
❌ Obě bratři přišli.
Incorrect — bratři is masculine, so the form is oba, not obě.
✅ Oba bratři přišli.
Both brothers came.
❌ Oba sestry mluví německy.
Incorrect — sestry is feminine, so it takes obě, not oba.
✅ Obě sestry mluví německy.
Both sisters speak German.
❌ Mluvil jsem s oba rodiči.
Incorrect — in the instrumental the determiner declines to oběma.
✅ Mluvil jsem s oběma rodiči.
I spoke with both parents.
❌ Přišlo oba kamarádi.
Incorrect — oba takes a plural verb, and masculine animate needs -i: přišli.
✅ Přišli oba kamarádi.
Both friends came.
❌ Držela to oběma rukami.
Incorrect — the pair 'hands' keeps the dual instrumental: rukama.
✅ Držela to oběma rukama.
She held it with both hands.
Key Takeaways
- As a determiner, oba/obě ("both") sits before a noun and picks out the two specific ones already in mind; the noun stays in the nominative plural.
- The gender split mirrors dva/dvě: oba for masculine, obě for feminine and neuter — only in the nominative/accusative.
- The verb is plural (masculine animate → -i: oba kamarádi přišli), unlike the singular-neuter genitive quantifiers.
- Oblique cases collapse to just two forms: obou (genitive/locative), oběma (dative/instrumental) — gender disappears here.
- Choose oba (the known pair) vs. dva (a bare count) vs. všichni (a larger whole set).
- Dual relics survive with paired body parts: oběma rukama, oběma očima.
- For the full declension and more on the dual relics, see the Numbers 'both' page.
Now practice Czech
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Start learning Czech→Related Topics
- 'Both': oba and oběB1 — The dual-origin word oba/obě, its gender split and special declension obou/oběma.
- 'All' and 'Whole': všechen, všechno, všichni, celýB1 — The forms of všechen by gender/number and how it differs from celý (whole).
- 'Each' and 'Every': každýA2 — každý means 'each / every', declines like a hard adjective, stays resolutely singular, and contrasts with collective všichni 'all'.
- Cardinal Numbers 0–4 and Nominative Plural AgreementA1 — jeden/dva/tři/čtyři, their gender forms, and why they take the nominative plural noun.
- Pointing With Determiners: ten, tento, tamten Before NounsA2 — Using the demonstratives as noun determiners to mark proximity and identifiability.