Takki on vedenpitävä.

Finnish does not normally use articles like the or a/an.

So takki can mean:

• a coat
• the coat
• just coat in a general sense

Which one is meant depends on the context. In a simple sentence like Takki on vedenpitävä, English might translate it as The coat is waterproof or A coat is waterproof, depending on the situation.

On is the 3rd person singular form of the verb olla, which means to be.

So:

• minä olen = I am
• sinä olet = you are
• hän on = he/she is
• takki on = the coat is

In this sentence, on simply means is.

Finnish very often forms compound words, much more freely than English does.

Vedenpitävä is a compound adjective:

• veden = of water / water’s
• pitävä = holding, keeping

Together, vedenpitävä literally means something like water-holding or keeping water out, which corresponds to waterproof.

In English, we often use one word like waterproof too, so this is actually a fairly easy compound to understand.

The basic form of water is vesi. In compounds like this, Finnish often uses another form of the noun instead of the dictionary form.

Here:

• vesi = water
• veden = of water

So vedenpitävä literally means water-of keeping → waterproof.

This change happens because vesi is one of the nouns whose stem changes:

• nominative: vesi
• genitive: veden

That is a normal pattern for this word, even though it may look irregular at first.

Yes, historically and grammatically it is the genitive form of vesi.

The genitive often corresponds to of in English, so:

• veden = of water

In compounds, Finnish commonly uses this kind of form as the first part of the compound. So vedenpitävä contains veden- rather than vesi-.

You do not need to think of it as a separate word in the sentence, though. The whole adjective vedenpitävä functions as one unit meaning waterproof.

Pitävä comes from the verb pitää, which has several meanings, including to hold, to keep, or to retain in different contexts.

As an adjective-like form, pitävä often means something like:

• holding
• keeping
• not letting through
• secure / firm in some contexts

So in vedenpitävä, it gives the idea of something that keeps water out or does not let water through.

Yes. In Finnish, adjectives usually agree with the noun in number and case.

In your sentence:

• takki is singular nominative
• vedenpitävä is also singular nominative

For example:

• Takit ovat vedenpitäviä. = The coats are waterproof.

There:

• takit = coats
• vedenpitäviä = waterproof, in plural partitive/nominative-predicate context as required by the structure

So yes, the adjective can change form. In this simple sentence, though, the basic form vedenpitävä is used.

This is the most neutral word order:

• Takki = subject
• on = verb
• vedenpitävä = predicate adjective

So it is structurally like English:

• The coat is waterproof.

Finnish word order is more flexible than English, but changing it usually affects emphasis.

For example:

• Takki on vedenpitävä. = neutral statement
• Vedenpitävä takki on. = unusual, marked emphasis
• Onko takki vedenpitävä? = Is the coat waterproof?

So the original order is the standard, natural one for a basic statement.

A helpful approximate pronunciation is:

VEH-den-PIH-tah-vah

A few useful points:

• e is like the e in bet, but pure and short unless doubled
• i is like ee in see, but shorter
• ä is a front vowel somewhat like a in some pronunciations of cat, but not exactly the same
• stress in Finnish usually falls on the first syllable: VEdenpitävä

So:

• takki ≈ TAHK-kee
• on ≈ on
• vedenpitävä ≈ VEH-den-PIH-tah-vah

Because this is a basic predicate adjective in the nominative singular.

In Takki on vedenpitävä:

• takki is singular
• the sentence is an ordinary positive statement
• the adjective appears in its basic form

Finnish does not add a special ending just because the adjective comes after is. Instead, the form depends on case, number, and sentence structure. Here the basic nominative singular is the correct form.

Yes.

You can say:

• vedenpitävä takki = a waterproof coat

That is the attributive use, where the adjective comes before the noun.

Your original sentence uses the predicate use:

• Takki on vedenpitävä. = The coat is waterproof.

Both are completely normal:

• vedenpitävä takki
• Takki on vedenpitävä.

Takki can cover a range that overlaps with English coat and jacket, depending on context.

It is a general word for an outer garment with sleeves. In real usage, the exact English translation may vary:

• coat
• jacket
• sometimes another similar outerwear word depending on style and context

So if the meaning shown to the learner is coat, that is fine, but in other contexts jacket may also be a natural translation.

Yes, this is a very productive pattern in Finnish.

Examples:

• tuulenpitävä = windproof
• pitävä can also appear in other compounds meaning something that holds or resists something
• vedenkestävä = water-resistant / water-repellent, literally something like withstanding water

This is useful because once you recognize compounds, many long Finnish words become easier to understand by parts.