Possessive adjectives derived from nouns

In English you say my brother's watch or Ana's bag: the owner gets 's. Serbian has the genitive for this (sat mog brata), but when the owner is one particular person, people much prefer something shorter: they turn the owner's noun into an adjective. Brat becomes bratov ("brother's"), sestra becomes sestrin ("sister's"), Ana becomes Anin ("Ana's"). Bratov sat — brother's watch. Anina torba — Ana's bag.

These words are called possessive adjectives formed from nouns. They work exactly like njegov and njen, which you already know: they stand before the thing owned and agree with it.

Step 1: build the adjective from the owner

• -ev is simply -ov after a soft sound: prijatelj + ov would be hard to say, so it becomes prijateljev. A final c turns into č first and then takes -ev: otac → očev (father's), stric → stričev (uncle's).
• -in goes with every noun ending in -a, including the masculine ones: tata is a man, but the word ends in -a, so it is tatin, never tatov.
• The final -a of the owner drops before -in: sestra → sestrin, žena → ženin.
• Before -in, a stem ending in -ica or -jka usually softens to č: drugarica → drugaričin, majka → majčin. Tetka and baka keep their k: tetkin, bakin.

Step 2: agree with the thing owned

The ending you just built tells you WHO owns it. The last vowel you add tells you WHAT is owned: it follows the gender of the possessed noun, exactly like njegov / njegova / njegovo. The owner's gender plays no part in this second step.

The classic mistake is to agree with the owner. Sestra is feminine, but her watch is masculine: sestrin sat, not sestrina sat. Brat is masculine, but his bag is feminine: bratova torba. Look at the thing, not the person.

In the other cases these adjectives take the same endings as njegov: a feminine object is bratovu jaknu, sestrinu knjigu; a masculine thing as object stays bratov kišobran; in the genitive, bratovog, sestrinog.

Capital letters with names

An adjective made from a personal name keeps the name's capital letter: Markov telefon, Anina narukvica, Nikolino pismo. One made from an ordinary noun is written small: bratov, mamin.

When NOT to use it

This adjective is made only from a noun for one person (or an animal: mačka → mačkin). For a thing, or for several owners, use the genitive after the noun instead:

• one person: bratova kuća (my brother's house)
• several people: kuća mojih roditelja (my parents' house) — no adjective from roditelji
• a thing: ključ od stana, boja torbe (the key of the flat, the colour of the bag)

If the owner has an adjective or pronoun of their own — my older brother's — Serbian usually switches to the genitive: sat mog starijeg brata. The possessive adjective is for a bare owner: bratov, mamin, Markov.