A mennyezet is nedves.

No. In this sentence, is does not mean the verb is.

Hungarian is is a small particle meaning too, also, or as well.

So:

• A mennyezet nedves. = The ceiling is wet.
• A mennyezet is nedves. = The ceiling is wet too / The ceiling is also wet.

This is one of the first things English speakers have to get used to, because Hungarian is looks exactly like English is, but it has a completely different job here.

Because Hungarian often leaves out the verb to be in the present tense, third person when the predicate is a noun or adjective.

So Hungarian says:

• A mennyezet nedves.
  literally: The ceiling wet.

This is normal and grammatical in Hungarian.

But in other tenses, or with some other persons, the verb appears:

• A mennyezet nedves volt. = The ceiling was wet.
• Nedves vagyok. = I am wet.
• Nedves vagy. = You are wet.

So in your sentence, the missing is is not an omission in the casual sense; it is simply how Hungarian grammar works.

A is the definite article, meaning the.

Hungarian has two forms of the definite article:

• a before consonant sounds
• az before vowel sounds

Since mennyezet begins with a consonant sound, it takes a:

• a mennyezet = the ceiling

Compare:

• az ablak = the window

Mennyezet means ceiling.

In this sentence it is in its basic dictionary form: singular, nominative.

A useful pronunciation note for English speakers:

• ny in Hungarian is a separate sound, roughly like the ny in canyon
• so mennyezet is approximately pronounced MEN-nyeh-zet

Not exactly English, of course, but that approximation helps.

Because Hungarian is usually comes right after the word or phrase it applies to.

So:

• A mennyezet is nedves.

means that the ceiling is the thing being added:
The ceiling too is wet / The ceiling is also wet

This suggests that something else was already mentioned as wet, and now the speaker adds the ceiling to that list.

So the placement matters:

• mennyezet is = the ceiling too

That is a very common Hungarian pattern.

Usually, yes.

Because is means also/too, it normally adds information to something already known or already mentioned.

So A mennyezet is nedves. usually implies a context like:

• The wall is wet, and the ceiling is wet too.

Hungarian is often depends on context in exactly this way. Without context, the sentence is still grammatical, but it naturally sounds like part of a larger conversation.

Yes:

• A mennyezet nedves. = The ceiling is wet.

This is the plain, neutral statement.

Adding is changes the meaning to also/too:

• A mennyezet is nedves. = The ceiling is wet too.

So is is not required grammatically, but it adds an important meaning.

Yes. Nedves is a fairly general word and can often be translated as wet, damp, or sometimes moist, depending on context.

For example:

• a nedves fal = a damp/wet wall
• nedves ruha = wet clothes
• nedves levegő = humid/moist air in some contexts

So in your sentence, the exact English choice depends on the situation, even though the Hungarian word stays the same.

Yes, Hungarian word order is quite flexible, and changing it often changes emphasis.

The version you have:

• A mennyezet is nedves.

puts the also/too idea on the ceiling.

A more neutral statement would be:

• A mennyezet nedves.

Another possible order:

• Nedves a mennyezet.

This can sound more like emphasizing wet or answering a question such as What’s wrong with the ceiling?

So Hungarian word order is not random; it often reflects what is new, important, contrasted, or added.

A rough guide is NED-vesh.

A few useful points:

• e is like e in bed
• s in Hungarian is pronounced like English sh

So nedves sounds approximately like NED-vesh.

That final s = sh rule is very important in Hungarian, because it surprises many English speakers at first.