Společenská místnost je otevřená.

Because společenská is an adjective modifying místnost, and Czech adjectives must agree with the noun in gender, number, and case.

• místnost is feminine singular
• so the adjective also takes the feminine singular form: společenská

The basic dictionary form is společenský. Its forms include:

• masculine: společenský
• feminine: společenská
• neuter: společenské

So here, společenská místnost is correct because místnost is feminine.

For the same reason: it agrees with místnost.

In Společenská místnost je otevřená, the word otevřená is an adjective meaning open, and it describes the feminine noun místnost. So it must also be in the feminine singular form.

Compare:

• obchod je otevřený = the shop is open
• restaurace je otevřená = the restaurant is open
• okno je otevřené = the window is open

The ending changes depending on the noun’s gender.

Je is the 3rd person singular form of být, meaning to be.

So:

• je = is

Czech often omits subject pronouns like he, she, or it, but it normally keeps the form of to be in sentences like this.

So the structure is:

• Společenská místnost = the common room / lounge
• je = is
• otevřená = open

Together: The common room is open.

Czech does not have articles like a or the.

English says:

• the common room is open
• a room is open

Czech usually leaves that distinction to the context.

So Společenská místnost je otevřená can mean The common room is open, and the definiteness comes from the situation, not from a separate word.

This is very normal in Czech.

Yes, it is a common expression.

Společenská místnost usually refers to a common room, lounge, social room, or recreation room in a school, hostel, hotel, community center, dormitory, and so on.

Literally:

• společenská relates to social / communal
• místnost = room

So the phrase is not just any random combination of words; it is a normal Czech way to refer to that kind of room.

You mostly just have to learn the grammatical gender of nouns as part of the word.

Místnost is feminine because that is how Czech classifies it grammatically. A helpful clue is that many feminine nouns end in:

• -ost
• -nost
• -st

So nouns like these are often feminine:

• radost = joy
• možnost = possibility
• místnost = room

Even though grammatical gender does not always match biological sex or any logical category, it matters because adjectives and some verbs or pronouns must agree with it.

Yes, you can, but it sounds a bit more formal, written, or official.

There are two common ways to say this idea:

• je otevřená — ordinary adjective, very natural in everyday speech
• je otevřena — shorter predicative form, often more formal or official

In everyday conversation, je otevřená is usually the safer and more natural choice.

You may also see signs or notices with:

• Otevřeno = Open

That is another common way to express the idea, especially on signs.

Both can often be translated as is open, but they work differently.

Je otevřená

• is an adjective agreeing with a noun
• matches the gender and number of the noun
• here it agrees with místnost

Je otevřeno

• is a more general, impersonal expression
• very common on signs and notices
• does not agree with a specific noun in the same way

So:

• Společenská místnost je otevřená = The common room is open.
• Ve společenské místnosti je otevřeno would sound odd, but Máme otevřeno or a sign Otevřeno is normal.

If you are talking directly about a specific feminine noun, otevřená is the straightforward choice.

A rough English-friendly guide would be:

spo-le-chen-skaa mee-stnost ye o-tev-rzhe-naa

A few useful pronunciation notes:

• Czech stress is usually on the first syllable of each word:
  • SPO-le-čens-ká
  • MÍST-nost
  • JE
  • O-tev-ře-ná
• č sounds like ch in church
• ř is a special Czech sound with no exact English equivalent; learners often approximate it at first
• á is a long vowel, so it is held a little longer than a

You do not need perfect ř immediately; Czech speakers will usually understand you if the rest is clear.

Yes. Czech word order is more flexible than English, because the grammar is shown partly by endings rather than only by position.

The neutral order here is:

• Společenská místnost je otevřená.

But other orders are possible for emphasis or style, for example:

• Otevřená je společenská místnost.
• Je otevřená společenská místnost? = Is the common room open?

Even though other orders are possible, the original sentence is the most natural neutral statement for a learner to use.

Normally, no.

In present-tense sentences with to be, Czech usually keeps the verb form:

• Místnost je otevřená.

Leaving out je would sound incomplete in standard Czech.

This is different from some languages where the present tense of to be can be omitted. In Czech, in a sentence like this, you should keep it.

It is in the nominative singular.

That is because it is the subject of the sentence:

• Společenská místnost = the thing being talked about
• je otevřená = what is being said about it

Both the noun and its adjective are nominative singular feminine:

• společenská
• místnost

And otevřená is also feminine singular nominative because it describes the subject after je.

Grammatically yes, but it means something different in emphasis and is not the normal way to express the idea of a common room.

• společenská místnost is a set phrase meaning common room / lounge
• místnost je společenská would mean something like the room is social / meant for social use, which sounds unusual in most contexts

So if you want the noun phrase common room, keep the words together:

• společenská místnost

That is the standard expression.