The relative pronoun 'koji' in the instrumental
As you know, the relative pronoun koji (who, which, that) agrees in gender and number with the noun it refers to, but its case depends on its role in the relative clause.
When describing the tool or means used to perform an action—like the keyboard you write with or the saw you cut with—the relative pronoun takes the instrumental case. When expressing a tool, we do not use a preposition in Croatian.
Here are the singular and plural instrumental forms:
| Gender | Instrumental Form |
|---|---|
| Masculine / Neuter | kojim |
| Feminine | kojom |
| Plural (All Genders) | kojima |
For feminine nouns, use kojom:
| Although it's old, that's the keyboard I'm writing a book with. | Iako je stara, to je tipkovnica kojom pišem knjigu. |
| This is the needle I'll fix the coat with. | Ovo je igla kojom ću popraviti kaput. |
For masculine and neuter nouns, use kojim:
| I need a strong thread I can fix the bag with. | Treba mi jak konac kojim mogu popraviti torbu. |
When referring to multiple items, the plural form kojima is used for all genders:
| A shovel and a saw are tools a worker builds a house with. | Lopata i pila su alati kojima radnik gradi kuću. |
The relative pronoun 'koji' in the dative
The dative case is used for the indirect object, usually the recipient of an action. When you talk about the person you are sending a document to, giving a gift to, or helping, the relative clause requires the dative case.
Here are the dative forms. Notice that the plural form is exactly the same as the instrumental plural!
| Gender | Dative Form |
|---|---|
| Masculine / Neuter | kojem |
| Feminine | kojoj |
| Plural (All Genders) | kojima |
For masculine and neuter nouns, use kojem:
| That is the coworker to whom I sent the document yesterday. | To je suradnik kojem sam jučer poslao dokument. |
| This is the new assistant the coworker will explain the task to. | Ovo je novi pomoćnik kojem će suradnik objasniti zadatak. |
For feminine nouns, the dative form is kojoj:
| In January I am traveling to the cousin I am bringing a special gift to. | U siječnju putujem k rođakinji kojoj nosim poseban poklon. |
| Did the cousin you helped give you anything? | Je li ti išta poklonila rođakinja kojoj si pomogao? |
And for plural nouns of any gender, use kojima:
| Those are the people we bring food to every week. | To su ljudi kojima svaki tjedan nosimo hranu. |