Learn Hardcore Croatian: S prijateljicom idem ravno do kina. - I am going straight to the cinema with my female friend.

Both are possible, but the default is s. Croatian uses the longer form sa mainly to make pronunciation easier before words that start with s, š, z, ž, or certain consonant clusters (e.g., sa sestrom, sa mnom, sa psom). Since prijateljicom starts with p + r, s prijateljicom is standard and smooth. You may still hear sa prijateljicom in speech; it isn’t wrong, just less necessary here.

What case is prijateljicom, and why does it end in -om?

It’s the instrumental case, used after the preposition s/sa meaning “with.” Feminine nouns in -a (like prijateljica) take -om in the instrumental singular: prijateljica → prijateljicom. So s prijateljicom = “with a (female) friend.”

How would I say “with a male friend”?

Use the masculine noun prijatelj in the instrumental: s prijateljem.
Examples:

S prijateljem idem do kina. = I’m going to the cinema with a (male) friend.
Plural: s prijateljima (male/mixed group), s prijateljicama (female group).

What does do mean here, and which case does it require?

Do means “to, up to, as far as,” and it always takes the genitive.

kino (nominative) → kina (genitive)
Hence: do kina = “to the cinema (up to it).”

What’s the difference between do kina and u kino?

do kina (genitive): up to the cinema, to its location/entrance; it doesn’t necessarily imply going inside.
u kino (accusative): into the cinema (motion into the interior).
So “Idem do kina” can mean “I’m going to the cinema (place/area),” while “Idem u kino” is “I’m going (in) to the cinema (to watch a film).”

Can I change the word order? For example: Idem s prijateljicom ravno do kina?

Yes. Croatian word order is flexible. All of these are natural, with slight shifts in emphasis:

S prijateljicom idem ravno do kina. (Fronts who you’re with.)
Idem s prijateljicom ravno do kina. (Neutral, very common.)
Idem ravno do kina s prijateljicom. (Adds the companion at the end.)
Ravno idem s prijateljicom do kina. (Emphasizes “straight.”)

What does ravno add here? Is it the same as pravo or direktno?

ravno = straight (ahead), referring to direction/path.
pravo is often used colloquially for “straight” too: ići pravo.
direktno = directly (without stops/detours), not strictly about a straight physical line. In many contexts ravno and pravo overlap; direktno focuses on not making stops.

Why is there no word for “a” in “with a friend”?

Croatian has no articles (no “a/an/the”). S prijateljicom can mean “with a friend” or “with the friend,” depending on context. Definiteness is inferred from context or made explicit with possessives or other details.

How do I say “with my friend” correctly—s mojom prijateljicom or sa svojom prijateljicom?

Both are possible. When the possessor is the subject (I’m going with my own friend), Croatian prefers the reflexive possessive svoj:

Preferred: sa svojom prijateljicom (or s svojom, though many choose sa for easier pronunciation there)
Also accepted: s mojom prijateljicom
Using svoj avoids ambiguity about whose friend it is.

How is idem formed, and what are the other present forms of ići?

Idem is 1st person singular present of ići (to go). Present forms:

ja idem
ti ideš
on/ona/ono ide
mi idemo
vi idete
oni/one/ona idu

Does the present tense idem mean I’m going right now or in the near future?

Both are possible. Croatian present often covers “I’m going (now)” and near-future plans (“I’m going soon”). For a clear future, you can use the future tense or a perfective verb:

Ići ću do kina. (I will go.)
Otići ću do kina. (I will set off/go.)
Perfective forms (like otići, poći) stress the completed action/set-off.

Why is it kina here but u kinu when I say “in the cinema”?

Different cases:

do kina uses the genitive (kina) after do.
u kinu uses the locative (kinu) after u when expressing location (in).
For motion into: u kino (accusative, same as nominative for neuter).

Could I say idem ravno kino without do?

No. You need a preposition. Use:

idem do kina (to the cinema)
idem u kino (into the cinema)
Bare accusative without the preposition isn’t grammatical here.

How do I pronounce tricky parts like s prijateljicom?

s is a clear “s.”
pr is a consonant cluster; roll the r lightly.
lj in prijateljicom is a palatal sound (like the “lli” in “million” but single).
c is “ts” (so -com sounds like “-tsom”).
ravno has a rolled r; both vowels are short and clear.

Does s ever mean “from” in Croatian?

Yes, s/sa can also mean “from/off (a surface or place) when used with the genitive (not the instrumental). For example:

s krova = from the roof (genitive).
In your sentence it’s “with,” so it governs the instrumental: s prijateljicom.

How would I say “from the cinema” vs “out of the cinema”?

od kina = from (the vicinity of) the cinema, as a starting point.
iz kina = out of the cinema (from inside it).
s/sa isn’t used for “from” with buildings you’re inside; use iz.