The stroj ("machine") paradigm is the soft counterpart of the hard hrad pattern. It declines masculine inanimate nouns — things, places, and abstractions, never living beings — whose stem ends in a soft consonant (ž, š, č, ř, c, j, ď, ť, ň). It covers a great many everyday objects: počítač (computer), klíč (key), čaj (tea), pokoj (room), kraj (region/edge), koš (basket), meč (sword), nůž (knife), and déšť (rain).
The good news for the learner is that stroj is one of the easiest paradigms in the whole noun system, because soft endings come in fewer flavours than hard ones. Where the hard hrad pattern makes you choose between -u and -a in the genitive, and between -ě and -u in the locative, stroj has a single answer for each: -e in the genitive, -i in the dative and locative. There are no splits to memorise.
The full stroj paradigm
Here is stroj through all seven cases, singular and plural, with the question each case answers.
| Case | Singular | Plural |
|---|---|---|
| Nominative (kdo? co?) | stroj | stroje |
| Genitive (koho? čeho?) | stroje | strojů |
| Dative (komu? čemu?) | stroji | strojům |
| Accusative (koho? co?) | stroj (= nominative) | stroje |
| Vocative (oslovení) | stroji | stroje |
| Locative (o kom? o čem?) | (o) stroji | (o) strojích |
| Instrumental (kým? čím?) | strojem | stroji |
Look at the economy: stroje is at once the nominative, accusative, and vocative plural and the genitive singular, while stroji covers the dative, locative, and vocative singular plus the instrumental plural. The whole paradigm runs on a handful of forms.
The inanimate accusative equals the nominative
Because stroj denotes a thing, it follows the iron rule of inanimate masculines: as a direct object it does not change. The accusative is identical to the nominative.
Kupuji nový počítač, ten starý je pomalý.
I'm buying a new computer, the old one is slow. (počítač, unchanged as object)
Podej mi prosím ten klíč.
Pass me that key, please. (klíč, unchanged as object)
Dám si zelený čaj.
I'll have a green tea. (čaj, unchanged as object)
Set this against the animate soft pattern muž, where the accusative takes -e (vidím muže). A machine and a man both end in a soft consonant, but only the living one changes in the accusative — that is animacy at work, and it is covered in full on the masculine animacy page.
Soft -e and -i where hrad has splits
The real selling point of stroj is how it tidies up the messy hard pattern. Compare the two inanimate masculines directly:
| Form | Hard — hrad | Soft — stroj |
|---|---|---|
| Genitive sg | hradu (or -a) | stroje |
| Dative / locative sg | hradu / hradě | stroji |
| Nominative / accusative pl | hrady | stroje |
| Locative pl | hradech | strojích |
So "of the machine" is stroje (one fixed form, no -u/-a choice), "in the machine" is ve stroji (no -ě/-u choice), the plural subject is stroje (soft -e, not hard -y), and "about the machines" is o strojích (soft -ích, not hard -ech). The instrumental singular strojem and the genitive/dative plural strojů/strojům are shared with hrad.
Zámek od toho pokoje se nedá otevřít.
The lock on that room can't be opened. (pokoj → pokoje, genitive singular -e)
Na klíči visela malá baterka.
A little flashlight hung on the key. (klíč → klíči, locative singular -i)
V dílně stály tři velké stroje.
Three big machines stood in the workshop. (stroj → stroje, nominative plural -e)
O těch nových počítačích se hodně mluví.
There's a lot of talk about those new computers. (počítač → počítačích, locative plural -ích)
Vowel shortening: nůž → nože
A handful of common stroj-type nouns shorten a long root vowel once an ending is added. The clearest is nůž ("knife"): the long ů of nůž becomes a short o everywhere except the nominative and accusative singular — nože, noži, nožem, nože — and then the genitive plural restores the long vowel as nožů.
There is a spelling subtlety worth pointing out. At the very end of nůž, the ž is pronounced [š] through Czech's regular word-final devoicing, so the word sounds like "núš." But it is spelled ž throughout the paradigm, and between vowels (nože) it is both spelled and pronounced as a voiced [ž]. Trust the spelling, not your ear: the stem consonant is ž.
Ten nůž je strašně tupý, ukroj to radši tímhle.
That knife is terribly blunt, better cut it with this one. (nůž, accusative = nominative)
Špička nože se ulomila.
The tip of the knife broke off. (nůž → nože, genitive; ů→o)
V kuchyni nám chybí pár ostrých nožů.
We're missing a few sharp knives in the kitchen. (nůž → nožů, genitive plural restores ů)
Common mistakes
❌ Vidím nového počítača.
Incorrect — počítač is inanimate, so the accusative equals the nominative; no -e is added.
✅ Vidím nový počítač.
I see a new computer. (počítač unchanged, adjective in inanimate accusative)
❌ Bydlím v malém pokoju.
Incorrect — the locative singular of a soft masculine is -i, not the hard -u: v pokoji.
✅ Bydlím v malém pokoji.
I live in a small room. (pokoj → pokoji)
❌ V dílně byly tři stroji.
Incorrect — the nominative plural of a soft inanimate is -e, not the animate -i: stroje.
✅ V dílně byly tři stroje.
There were three machines in the workshop. (stroj → stroje)
❌ Mluvíme o těch klíčech.
Incorrect — a soft stem takes -ích in the locative plural, not the hard -ech: o klíčích.
✅ Mluvíme o těch klíčích.
We're talking about those keys. (klíč → klíčích)
❌ Nemám doma žádné ostré núže.
Incorrect — the plural keeps the spelling nože (with short o and ž), even though nůž shortens; the noun is nože, never *núže.
✅ Nemám doma žádné ostré nože.
I don't have any sharp knives at home. (nůž → nože)
The thread is the same as with muž: do not pour hard hrad endings into a soft mould. A soft inanimate wants -e in the genitive, -i in the dative/locative, -e in the nominative plural, and -ích in the locative plural.
Key takeaways
- stroj is the model for soft masculine inanimate nouns: počítač, klíč, čaj, pokoj, kraj, koš, nůž.
- The accusative equals the nominative (vidím stroj) — the inanimate signature, the mirror image of soft animate muž (vidím muže).
- Stroj has no splits: genitive singular is always -e (stroje), dative/locative always -i (stroji) — far simpler than hard hrad.
- The nominative/accusative plural is soft -e (stroje), and the locative plural is -ích (strojích, not strojech).
- A few nouns shorten a long vowel before endings: nůž → nože (with the genitive plural nožů restoring the long ů).
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Start learning Czech→Related Topics
- Masculine Inanimate: The Hrad ParadigmA2 — The hard masculine inanimate pattern hrad (castle) — the model for consonant-final non-living masculines, with its full seven-case table and the all-important inanimate accusative.
- Masculine Animate: The Muž ParadigmA2 — The soft masculine animate pattern muž (man) — the model for animate masculines ending in a soft consonant, with its full seven-case table and the soft/hard contrast against pán.
- The -e/-ě vs -u Locative of Inanimate MasculinesB2 — Choosing the locative singular ending for hard inanimate masculines and the alternations -ě triggers.
- The -u vs -a Genitive of Inanimate MasculinesB2 — Why some inanimate masculines take genitive -a (lesa) while most take -u (hradu).
- Masculine Animacy: Životná vs NeživotnáA2 — Why Czech masculine nouns split into animate (living) and inanimate, and how that split changes the accusative singular, the nominative plural, and all the agreement around them.