Learn Hardcore Croatian: On je zadovoljan.

On – he
je – is (3rd person singular of biti – to be)
zadovoljan – satisfied / pleased / content (masculine singular form of the adjective)

So the literal structure is He is satisfied.

Do I always need to say on, or can I leave it out?

Croatian usually omits subject pronouns when they are clear from context.

Full form: On je zadovoljan. – He is satisfied.
Very natural in context: Zadovoljan je. – (Literally) Satisfied is. → He is satisfied.

Key points:

You normally do not say je zadovoljan by itself; je is a clitic and cannot stand first in the sentence.
If it is already clear you are talking about a man, the most natural short version is Zadovoljan je.
You keep On je zadovoljan. when you:
- introduce someone for the first time, or
- want to contrast (On je zadovoljan, ali ona nije. – He is satisfied, but she is not.)

Why does zadovoljan end in -an? Are there feminine or neuter forms?

Zadovoljan is an adjective and it agrees in gender, number, and case with the noun (or pronoun) it describes.

Basic singular forms:

Masculine: zadovoljan
- On je zadovoljan. – He is satisfied.
Feminine: zadovoljna
- Ona je zadovoljna. – She is satisfied.
Neuter: zadovoljno
- Dijete je zadovoljno. – The child is satisfied.

So -an / -na / -no mark masculine / feminine / neuter here.

How would the sentence change if the subject were female?

You change both the pronoun and the adjective to the feminine:

Ona je zadovoljna. – She is satisfied.

Breakdown:

Ona – she
je – is
zadovoljna – satisfied (feminine singular)

Can the word order change? For example, can I say On zadovoljan je or Zadovoljan je on?

Croatian word order is flexible, but je has a special rule: it is a clitic and must appear in the second position in the clause.

Natural options:

On je zadovoljan. – neutral, most common.
Zadovoljan je. – normal, with light emphasis on the adjective (often used without the pronoun).
On je zadovoljan, a ne ljut. – He is satisfied, not angry.

Marked but possible (for strong emphasis, often spoken):

Zadovoljan je on, ali ja nisam. – He is satisfied, but I am not. (Emphasizing on.)

Unnatural / wrong in standard language:

On zadovoljan je. ✗ – je is too late; it should come earlier.

So, remember: je should be near the beginning, in the second slot, but the rest can move for emphasis.

What is the infinitive of je, and how do you conjugate this verb?

The infinitive is biti – to be.

Present tense of biti:

ja sam – I am
ti si – you are (singular, informal)
on/ona/ono je – he/she/it is
mi smo – we are
vi ste – you are (plural or formal)
oni/one/ona su – they are (masc / fem / neuter)

So je is simply the 3rd person singular present of biti.

How do I say He was satisfied or He will be satisfied?

Past (He was satisfied):

On je bio zadovoljan.
More natural in speech: Bio je zadovoljan.

Here:

bio – past tense form of biti (masculine)
je – auxiliary
zadovoljan – satisfied

Future (He will be satisfied):

On će biti zadovoljan.
Shorter / more typical: Bit će zadovoljan.

Here:

će – future auxiliary (clitic)
biti – infinitive to be

Note clitic behavior again: će tends to appear in the second position, which is why Bit će zadovoljan is very common.

How do I make this sentence negative?

Use the negative form of biti:

On nije zadovoljan. – He is not satisfied.

Negative present forms of biti:

nisam – I am not
nisi – you are not
nije – he/she/it is not
nismo – we are not
niste – you are not
nisu – they are not

So:

On nije zadovoljan. – He is not satisfied.
Ona nije zadovoljna. – She is not satisfied.

You cannot say something like on je ne zadovoljan; you must change je to nije.

Is zadovoljan the same as sretan, or is there a difference?

They overlap but are not identical:

zadovoljan – satisfied, content, pleased, usually about some specific result or situation
- On je zadovoljan poslom. – He is satisfied with the job.
sretan – happy, fortunate, more about general happiness or strong positive emotion
- On je sretan. – He is (a) happy (person) / He feels happy.
- Sretan sam što si došao. – I am happy that you came.

So On je zadovoljan. suggests he is content / pleased (with how something turned out), not necessarily deeply happy in general.

How do you pronounce On je zadovoljan?

Approximate pronunciation:

On je zadovoljan → [on je za-DOH-voh-lyan]

Syllable by syllable:

On – like on in English on, but with a clearer o.
je – like ye in English yes (but shorter).
zadovoljan – za-do-vo-ljan
- za – zah (short a)
- do – doh (stressed)
- vo – voh
- ljan – lyan (with lj as in the lli of million when pronounced clearly)

Phonetically simplified: ON-ye zah-DOH-voh-lyan.

Can I add very to say He is very satisfied?

Yes. Common adverbs are jako and vrlo:

On je jako zadovoljan. – He is very satisfied.
On je vrlo zadovoljan. – He is very satisfied. (a bit more neutral/formal)

In normal speech you will often drop the pronoun:

Jako je zadovoljan. – He is very satisfied.

The adverb jako/vrlo comes before the adjective.