Druga znanstvenica čita romane znanstvene fantastike i zamišlja svemirske gradove.

Druga is the feminine form of drugi, which literally means second.

However, in context it can also mean the other (as in the other scientist), especially if:

• there are exactly two people, and we’re distinguishing one from the first, or
• earlier context has already mentioned jedna znanstvenica (one scientist), and now we contrast her with druga znanstvenica (the other scientist).

So:

• druga znanstvenica can be understood as either:
  • the second (female) scientist, or
  • the other (female) scientist (when there are two).

Context decides which nuance is stronger.

Croatian adjectives and ordinal numbers agree in gender, number, and case with the noun they describe.

• znanstvenica = female scientist (feminine noun)
• znanstvenik = scientist (typically male, masculine noun)

Because znanstvenica is feminine singular, we must use the feminine form of second:

• masculine: drugi znanstvenik (second male scientist)
• feminine: druga znanstvenica (second female scientist)

So druga is simply agreeing with znanstvenica in gender (feminine), number (singular), and case (nominative).

Croatian has no articles (a, an, the). Definiteness/indefiniteness is usually understood from context, word order, and sometimes intonation.

So:

• druga znanstvenica can mean:

  • the other scientist
  • another scientist
  • a second scientist

• čita romane can mean:

  • she reads novels
  • she is reading (the) novels

If you want to make definiteness very clear, you usually rely on context or add extra words:

• ona druga znanstvenica – that other scientist
• te romane – those novels / those particular novels

Romane is the accusative plural of roman (novel).

The verb čita (reads, is reading) takes a direct object in the accusative case:

• singular: čita roman – she reads a novel
• plural: čita romane – she reads novels

So:

• nominative singular: roman (subject form)
• accusative plural: romane (object form after čitati)

Here we have a noun + descriptive genitive structure:

• romane – novels (accusative plural)
• znanstvene fantastike – of science fiction (genitive singular)

Znanstvena fantastika by itself (nominative) means science fiction as a genre:

• Volim znanstvenu fantastiku. – I like science fiction.

But after romane, we use the genitive to say novels of science fiction:

• romane (kakve?) znanstvene fantastike – novels of science fiction / science‑fiction novels

So:

• standalone genre name: znanstvena fantastika (nominative)
• as a descriptor after a noun: romani znanstvene fantastike, filmovi znanstvene fantastike, etc. (genitive)

The phrase znanstvene fantastike is in the genitive singular because it specifies the type of novels:

• romani znanstvene fantastike – literally novels of science fiction

This genitive of specification (or genitive of type) is very common:

• čaj mente – tea of mint → mint tea
• knjige povijesti – books of history → history books
• romani znanstvene fantastike – novels of science fiction → science‑fiction novels

So:

• fantastika (nominative singular) → fantastike (genitive singular)
• modified by znanstvene (genitive singular feminine adjective agreeing with fantastike)

The verb zamišljati (to imagine) also takes a direct object in the accusative, without a preposition:

• zamišljati nešto – to imagine something

So:

• svemirske gradove is the direct object in accusative plural:
  • nominative: svemirski gradovi – space cities (subject)
  • accusative: svemirske gradove – space cities (object)

No preposition is needed, just like English imagine cities or imagine worlds.

Svemirske comes from svemir (outer space, universe), so svemirski means space‑ or of outer space.

Agreement:

• noun: gradovi – masculine plural (cities)
• in accusative plural (as object): gradove
• adjective: svemirski (masc.) → in accusative plural masculine: svemirske gradove

So the pattern is:

• nominative plural: svemirski gradovi – space cities (as subject)
• accusative plural: svemirske gradove – space cities (as object)

Čitati and zamišljati are imperfective verbs, used here for general or repeated actions:

• (Ona) čita romane… i zamišlja…
  → She reads novels… and imagines… (habitually / regularly / generally)

If you used perfective forms, you’d change the meaning:

• pročita romane – she reads/finishes the novels (completed action)
• zamislit će svemirske gradove – she will imagine space cities (once / at some point)

In this sentence, the present imperfective describes what she typically does, so čita and zamišlja are appropriate.

Some changes are possible, but not all are natural.

Acceptable variations (with slightly different emphasis):

• Druga znanstvenica zamišlja svemirske gradove i čita romane znanstvene fantastike.
• Romane znanstvene fantastike čita druga znanstvenica i zamišlja svemirske gradove. (emphasis on the novels)

But znanstvene romane fantastike is not idiomatic; znanstvena fantastika functions as a fixed phrase (the genre name), and we normally keep znanstvene fantastike together in genitive after romane:

• natural: romane znanstvene fantastike
• unnatural/incorrect: znanstvene romane fantastike

The original word order is the most neutral and natural.