A kartondoboz nagy.

A is the Hungarian definite article, so it means the.

In Hungarian, the definite article has two forms:

• a before consonant sounds
• az before vowel sounds

So here it is a kartondoboz because kartondoboz starts with a consonant.

In Hungarian, the verb to be is usually omitted in the present tense, third person.

So:

• A kartondoboz nagy. = The cardboard box is big.

Literally, Hungarian is saying something like:

• The cardboard box big.

But this is completely normal Hungarian grammar.

The verb van or vannak appears in other situations, but not usually in simple present-tense sentences like this one.

Because here nagy is not directly describing the noun inside the noun phrase. It is the predicate adjective: it tells us what the box is like.

So Hungarian uses:

• A kartondoboz nagy. = The cardboard box is big.

But if you want to say the big cardboard box, where big directly modifies box, then the adjective goes before the noun:

• a nagy kartondoboz = the big cardboard box

So the position of the adjective changes depending on its job in the sentence.

Yes, kartondoboz is one word, and it is a compound noun.

It is made from:

• karton = cardboard
• doboz = box

So kartondoboz literally means cardboard box.

Hungarian often forms compound nouns this way, writing them as a single word.

The sentence A kartondoboz nagy. is the neutral, straightforward word order.

But Hungarian word order is fairly flexible, and changing it often changes the emphasis.

For example:

• A kartondoboz nagy. = neutral statement: The cardboard box is big.
• Nagy a kartondoboz. = puts more emphasis on big, something like The cardboard box is big or The box is big

So yes, the order can change, but the neutral beginner-friendly version is A kartondoboz nagy.

A simple pronunciation guide:

• a sounds like a short aw
• kartondoboz has stress on the first syllable: KAR-ton-do-boz
• nagy sounds roughly like nody or nawdy, but the gy is a special Hungarian sound

A few helpful points:

• Hungarian always stresses the first syllable of a word.
• The gy in nagy is a soft consonant, somewhat like the d in British duke or the sound in during for some speakers, though not exactly the same.

No. Hungarian has no grammatical gender, so adjectives do not change for masculine, feminine, or neuter.

So nagy stays nagy regardless of whether the noun refers to something masculine, feminine, or inanimate.

That is much simpler than in many Indo-European languages.

Grammatically, yes, but it means something different.

• A kartondoboz nagy. = The cardboard box is big.
• Egy kartondoboz nagy. = A cardboard box is big.

In real usage, egy often sounds less natural here unless the context makes it clear why you mean a certain unspecified cardboard box.

So if you are talking about a specific box already known in context, a is the natural choice.

It would be:

• A kartondobozok nagyok. = The cardboard boxes are big.

Here two things change:

• kartondoboz → kartondobozok = boxes
• nagy → nagyok = big for a plural predicate

This is useful to notice because in Hungarian, predicate adjectives can show plural.

Yes. A kartondoboz nagy. is a complete, correct, natural Hungarian sentence.

It is simple, neutral, and very typical of beginner examples because it shows several important patterns clearly:

• the definite article a
• a compound noun: kartondoboz
• omission of is
• a predicate adjective after the noun: nagy