A zajforrás a másik lakás.

In Hungarian, the verb to be is usually left out in the present tense, third person when the predicate is a noun or adjective.

So:

• A zajforrás a másik lakás. = The source of the noise is the other apartment.

But in other situations, van / vannak can appear, for example:

• A zajforrás a másik lakás volt. = The source of the noise was the other apartment.
• A zajforrás a másik lakás lesz. = The source of the noise will be the other apartment.

Also compare:

• A lakás csendes. = The apartment is quiet.
• A lakás nem csendes. = The apartment is not quiet.

In negative sentences, forms of to be may reappear depending on the structure, so this omission is something you learn as a pattern rather than a universal rule.

Both a words are the Hungarian definite article, meaning the.

So the sentence is structured like this:

• A zajforrás = the noise source
• a másik lakás = the other apartment

Hungarian often uses the definite article on both sides of this kind of sentence when both nouns are definite.

So this is completely normal:

• A tanár a szomszéd. = The teacher is the neighbor.
• A probléma a pénz. = The problem is the money.

English also has the twice in many similar sentences, so this part is actually fairly parallel.

Hungarian has two forms of the definite article:

• a before a consonant
• az before a vowel

Here:

• zajforrás starts with z, a consonant → a zajforrás
• másik starts with m, a consonant → a másik

Examples:

• a ház = the house
• a könyv = the book
• az autó = the car
• az ember = the person

So a zajforrás a másik lakás is exactly what you would expect.

It is a compound noun:

• zaj = noise
• forrás = source

So literally, zajforrás means noise-source, or more naturally in English, source of the noise / source of the noise problem.

Hungarian uses compound nouns very freely, much like German. Instead of saying something like source of the noise, Hungarian often packs the idea into one word.

Other similar compounds include:

• vízforrás = water source / spring
• hőforrás = heat source
• energiaforrás = energy source

So zajforrás is a very natural Hungarian-style compound.

This is a very common question.

• más means different or another
• másik means the other one / the other

In this sentence, a másik lakás means the other apartment, usually implying that there is another known apartment being contrasted with this one.

Compare:

• más lakás = a different apartment
• a másik lakás = the other apartment

So if there are two apartments in mind, a másik lakás strongly suggests the other one of the two or the other relevant one.

That is why másik is the natural choice here.

Because a másik lakás is a definite noun phrase: the other apartment.

In Hungarian, másik by itself does not automatically remove the need for the definite article. If you mean a specific, identifiable apartment, you normally say:

• a másik lakás = the other apartment

Without the article, másik lakás would sound more like:

• another apartment
• some other apartment
• a less definite expression, depending on context

So in this sentence, the speaker is talking about a specific apartment already understood from the situation.

It is in the nominative form, which is the basic dictionary form.

There is no special ending here because lakás is functioning as a predicate noun:

• A zajforrás = subject
• a másik lakás = predicate noun

Hungarian does not mark this with a separate case ending in this sentence.

So:

• lakás = basic form, apartment

If it were in another case, you would see an ending, for example:

• lakásban = in the apartment
• lakást = apartment as a direct object
• lakáshoz = to the apartment

But here it stays plain: lakás.

Yes, Hungarian word order is flexible, but changing it usually changes the focus or emphasis.

The original sentence:

• A zajforrás a másik lakás.

This presents the source of the noise as the topic, and identifies it as the other apartment.

You could also say:

• A másik lakás a zajforrás.

This is also grammatical, but now the other apartment is the starting point/topic, and you are saying that it is the noise source.

So the difference is not really basic meaning, but what the sentence is about first and what gets highlighted.

English often relies more on intonation or context for this; Hungarian uses word order much more actively for information structure.

Yes, the accents matter a lot in Hungarian because they usually mark different vowel lengths, and vowel length can change the word.

A rough pronunciation guide:

• zaj sounds roughly like zoy
• forrás sounds roughly like for-raash
• lakás sounds roughly like la-kaash
• másik sounds roughly like maa-shik

A few important points:

• á is a long vowel, different from a
• ó is a long vowel, different from o

So:

• forrás is not the same as forras
• lakás is not the same as lakas

Also, Hungarian stress is very regular: it falls on the first syllable of each word.

So:

• ZAJforrás
• MÁsik
• LAkás

That regular stress pattern is very helpful once you get used to it.

Both are possible, but they are slightly different in style and structure.

• a zajforrás = the noise source as a compact compound noun
• a zaj forrása = the source of the noise, using a possessed structure

The second one breaks down like this:

• a zaj = the noise
• forrása = its source / source of it

So a zaj forrása is often closer to the English structure the source of the noise.

Meanwhile, zajforrás is shorter and more lexicalized, like a standard compound noun. In many contexts, it sounds very natural and efficient.

So the sentence you were given is perfectly normal Hungarian.