Navodno je mač u muzeju.

Navodno means something like allegedly, reportedly, or supposedly.

It tells you that the speaker is not presenting the information as a confirmed fact. Instead, they are saying this is what people say, what has been reported, or what is believed.

So the sentence does not sound fully certain. It has a slight distance, like:

• Apparently, the sword is in the museum.
• The sword is supposedly in the museum.

Je is a clitic in Croatian. Clitics are short unstressed words that usually go in the second position in a clause.

So in:

Navodno je mač u muzeju.

the first element is navodno, and je comes right after it.

This is very normal in Croatian. English speakers often expect je to stay next to the subject, but Croatian word order is more flexible.

Je is the 3rd person singular present form of the verb biti (to be).

Here it means is.

So:

• je = is

In this sentence, it links mač and u muzeju, just like is in English:

• The sword is in the museum.

Because u can take different cases depending on the meaning.

Here, u means in a location, so it takes the locative case:

• muzej → u muzeju

So:

• u muzeju = in the museum

If you were talking about movement into the museum, Croatian would normally use the accusative:

• Idem u muzej. = I am going to the museum.

So the contrast is:

• u muzeju = in the museum, located there
• u muzej = into/to the museum, movement toward it

Mač is in the nominative singular.

It is the grammatical subject of the sentence:

• mač = the sword

Because Croatian often does not have articles like the or a, the bare noun mač can mean a sword or the sword, depending on context.

Yes. Mač is a masculine noun.

That matters for declension in other cases. For example, in singular:

• nominative: mač
• genitive: mača
• dative: maču
• accusative: mač
• locative: maču
• instrumental: mačem

In this sentence, though, you only need the nominative form mač.

Yes, Croatian word order is fairly flexible.

You could also say:

• Mač je navodno u muzeju.
• U muzeju je navodno mač.

These versions are not exactly identical in emphasis, but they are possible.

The original:

• Navodno je mač u muzeju.

puts navodno first, so the sentence begins with the idea of reported information or uncertainty.

That makes good sense if the speaker wants to highlight that this is only what has been said.

No, it does not have to come first, but it very often does.

You can move it depending on what you want to emphasize:

• Navodno je mač u muzeju.
• Mač je navodno u muzeju.

Both are natural. The difference is mostly about focus and rhythm.

When navodno is first, the sentence immediately sounds like this is only alleged/reported.

It sounds mostly neutral, but navodno can feel a bit more report-like, journalistic, or careful than plain everyday speech.

For example:

• Mač je u muzeju. = simple statement
• Navodno je mač u muzeju. = careful, reported, not fully confirmed

So it is perfectly normal Croatian, but the adverb gives it a slightly more detached tone.

No, not in standard Croatian.

In this sentence, je is necessary because it is the present form of to be.

So you need:

• Navodno je mač u muzeju.

not:

• Navodno mač u muzeju. ✗

Croatian can omit subject pronouns like on, ona, ja, but not the verb here.

Croatian usually does not use articles like English a and the.

So mač by itself can mean:

• a sword
• the sword

The context tells you which one is meant.

If the meaning has already been given to you as the sword, then that is how you should understand it in this sentence. But grammatically, Croatian does not mark that distinction directly with an article.

It can be used in different ways.

In your sentence, navodno simply modifies the whole statement:

• Navodno je mač u muzeju.

But you may also see related reporting structures in Croatian, for example with a clause:

• Navodno, mač je u muzeju.
• Kažu da je mač u muzeju. = They say that the sword is in the museum.

So navodno itself does not require da. It can stand on its own as an adverb meaning reportedly/allegedly.

A helpful rough pronunciation is:

• mu-ze-yu

More carefully, j in Croatian is pronounced like English y in yes.

So:

• muzej sounds roughly like moo-zay
• muzeju sounds roughly like moo-ZAY-yoo

And mač is pronounced approximately like mach, with č sounding like ch in church, but usually a bit firmer.