Njegova prijateljica je znanstvenica; za nju je znanost isto što i igra.

His friend is a scientist (female); for her, science is the same as a game.

Breakdown of Njegova prijateljica je znanstvenica; za nju je znanost isto što i igra.

• biti: to be
• njegov: his
• za: for
• nju: her
• igra: game
• prijateljica: female friend
• isto što i: the same as
• znanstvenica: scientist
• znanost: science

Questions & Answers about Njegova prijateljica je znanstvenica; za nju je znanost isto što i igra.

Why is it njegova prijateljica and not njegov prijatelj?

In Croatian, nouns referring to people usually show grammatical gender:

• prijatelj = (male) friend
• prijateljica = (female) friend

The possessive pronoun must agree in gender and number with the noun it modifies:

• njegov prijatelj – his (male) friend
• njegova prijateljica – his (female) friend

So njegova prijateljica tells you directly that the friend is female.

Why is it prijateljica je znanstvenica and not something like “prijateljica je a scientist”?

Croatian has no articles (a, an, the), so you simply use the noun:

• Ona je liječnica. – She is (a) doctor.
• Njegova prijateljica je znanstvenica. – His friend is (a) scientist.

The structure is:
[subject] + je + [noun in nominative case]

Both prijateljica and znanstvenica are in the nominative, because this is an equation with the verb biti (to be): one thing is the other.

What exactly does za nju mean, and why is it nju, not ona or njoj?

• ona = she (nominative, subject form)
• nju = her (accusative)
• njoj = to her / for her (dative)

After most prepositions, Croatian uses the accusative for meanings like “for, about, around” etc.
The preposition za (“for”) here takes the accusative:

• za koga? – for whom? → za nju – for her

So:

• Za nju je znanost isto što i igra.
  Literally: For her, science is the same as play.

You cannot say za ona or za njoj here; za nju is the correct form.

Can I change the word order in Za nju je znanost isto što i igra?

Yes. Croatian word order is flexible, and changes what is emphasized:

• Za nju je znanost isto što i igra.
  Neutral: For her, science is the same as play. (emphasis on “for her”)

• Znanost je za nju isto što i igra.
  Emphasis more on znanost (science): Science, for her, is the same as play.

• Znanost je isto što i igra za nju.
  Emphasis on za nju at the end.

All are grammatically correct. The original order highlights her personal perspective (za nju).

What does the phrase isto što i mean, and how does it work grammatically?

isto što i is a set phrase meaning “the same as”.

Breakdown:

• isto – the same
• što – what / which / that
• i – here works like “as” in this structure (literally “also/too”, but often used in comparisons like this)

In znanost je isto što i igra:

• znanost (science) = subject
• je = is
• isto = the same
• što i igra = as play

You can use it with other nouns:

• Za njega je posao isto što i hobi.
  For him, work is the same as a hobby.

Why is there i in isto što i igra? Could I just say isto što igra?

You normally keep the i in this pattern isto što i + noun/pronoun.

• isto što i igra – the same as play
• isto što i ja – the same as I / as me
• isto što i prije – the same as before

Saying isto što igra would sound wrong or at least very odd in standard Croatian. The i is part of the standard comparative structure here.

How is isto što i different from kao (as/like)?

Both can express similarity, but isto što i is stronger, closer to English “exactly the same as”:

• Znanost je za nju isto što i igra.
  Science is the same as play for her. (no real difference between the two in her mind)

• Znanost je za nju kao igra.
  Science is like a game to her. (comparison, but not necessarily complete equivalence)

So isto što i emphasizes identity/equivalence; kao emphasizes similarity.

Why are znanost and igra in the same form (no visible case endings)?

Both znanost and igra are in the nominative singular:

• znanost – nominative singular (feminine)
• igra – nominative singular (feminine)

Reasons:

1. After je (from biti, to be) in a sentence of the type X is Y, Croatian uses the nominative for both X and Y:

   • Ona je znanstvenica. – She is (a) scientist.
   • Znanost je igra. – Science is play.

2. In isto što i igra, the understood structure is:

   • isto što [je] i igra – the same as (it) is play
     So igra also stays in nominative.

There is no need for accusative or other cases here.

What’s the difference between znanost and nauka?

Both can mean science, but:

• znanost – standard, neutral word for science in Croatian.
• nauka – more typical in Serbian, Bosnian, Montenegrin; in Croatian it sounds archaic or regionally marked.

In standard Croatian you would normally say:

• ona radi u znanosti – she works in science
• prirodne znanosti – natural sciences

Does prijateljica mean “friend” or “girlfriend”?

By default, prijateljica means female friend (non-romantic).

Whether it implies “girlfriend” depends entirely on context. If you explicitly want “girlfriend”, other words are more direct:

• djevojka – girlfriend (literally “girl”), very common
• cura – girlfriend / girl (colloquial)

So:

• Njegova prijateljica je znanstvenica.
  → His (female) friend is a scientist.

• Njegova djevojka je znanstvenica.
  → His girlfriend is a scientist.

Could I say Ona je znanstvenica; za nju je znanost isto što i igra instead of Njegova prijateljica je znanstvenica?

Yes. That is perfectly correct:

• Ona je znanstvenica; za nju je znanost isto što i igra.
  She is a scientist; for her, science is the same as play.

Differences:

• Njegova prijateljica je znanstvenica – introduces her via her relationship to “him” (she is his friend).
• Ona je znanstvenica – just states who she is, without reference to another person.

Both are grammatically fine; the choice depends on what you want to emphasize.