A mentőmellény vízálló.

In Hungarian, the verb to be is usually left out in the present tense, third person when you are making a simple statement.

So:

• A mentőmellény vízálló. = The life jacket is waterproof.

But in other persons, Hungarian does use the verb:

• Vízálló vagyok. = I am waterproof.
• Vízálló vagy. = You are waterproof.
• Vízálló. = He/she/it is waterproof.

This omission is very normal in Hungarian and is one of the first things English speakers notice.

A is the Hungarian definite article, equivalent to the.

Hungarian has two forms of the:

• a before a consonant sound
• az before a vowel sound

Since mentőmellény begins with m, a consonant, the sentence uses:

• a mentőmellény = the life jacket

Compare:

• az alma = the apple
• a kabát = the coat

Because here vízálló is not just an adjective inside a noun phrase; it is the predicate of the sentence.

Structure:

• A mentőmellény = the subject
• vízálló = what is being said about the subject

So the sentence means:

• The life jacket is waterproof.

If you put the adjective before the noun, you no longer have a full sentence. You get a noun phrase instead:

• a vízálló mentőmellény = the waterproof life jacket

So:

• A mentőmellény vízálló. = complete sentence
• A vízálló mentőmellény. = not a normal complete sentence by itself

Yes, it is one word, and it is a compound noun, which is very common in Hungarian.

It is made from:

• mentő = rescue / saving
• mellény = vest

So literally it is something like rescue vest, which corresponds to life jacket in English.

Hungarian often builds everyday words this way, by combining simpler elements into one compound.

Vízálló is also a compound-style word.

It contains:

• víz = water
• álló = standing / resisting

Together, vízálló means waterproof or water-resistant, depending on context.

You will see the same pattern in other Hungarian adjectives:

• hőálló = heat-resistant
• tűzálló = fireproof / fire-resistant
• rozsdaálló = rustproof / stainless

So this is a useful pattern to recognize.

A rough pronunciation guide:

• mentőmellény ≈ MEN-tuh-mel-layny
• vízálló ≈ VEEZ-aal-loh

A few important vowel notes:

• é is like a long ay
• á is a long open a
• ó is a long o
• ő is a rounded vowel that English does not really have; it is somewhat like the vowel in French deux or German schön
• ny is like ny in canyon

Also, stress in Hungarian normally falls on the first syllable:

• MEN-tő-mellény
• VÍZ-álló

Hungarian adjectives generally do not agree with nouns in the way they do in many Indo-European languages.

So whether the noun is masculine, feminine, neuter, singular, or plural, the adjective usually stays the same basic form.

That means:

• vízálló mentőmellény = waterproof life jacket
• vízálló mentőmellények = waterproof life jackets

The adjective vízálló itself does not change here.

This is often easier for English speakers, since English adjectives also usually do not agree.

The neutral word order here is:

• A mentőmellény = topic / subject
• vízálló = comment / predicate

So the sentence has a very natural, plain structure:

• The life jacket is waterproof.

Hungarian word order is more flexible than English, but changes in order often affect focus or emphasis, not just style.

For example, this sentence in its given order sounds like a simple statement of fact.

Usually, if you mean the life jacket is waterproof, you would keep a.

Without the article, Mentőmellény vízálló sounds less natural as a normal standalone sentence. It could work only in special contexts, such as headings, labels, or very telegraphic style.

So for ordinary speech and writing, use:

• A mentőmellény vízálló.

Hungarian often uses articles in places where English learners might be tempted to leave them out.

Because mentőmellény is the subject of the sentence, and in Hungarian the subject is typically in the basic dictionary form.

There is no direct object here, so no accusative ending like -t is needed.

Compare:

• A mentőmellény vízálló. = The life jacket is waterproof.
• Látom a mentőmellényt. = I see the life jacket.

In the second sentence, mentőmellény becomes mentőmellényt because it is the direct object.

Yes, depending on context, vízálló can cover both ideas.

In everyday language, it is commonly used where English might say:

• waterproof
• water-resistant

The exact strength of the meaning depends on the situation. For example, in product descriptions, the technical standard may matter, but in normal conversation vízálló is the usual word.

So in this sentence, it simply tells you that the life jacket resists water.