To describe extended family members like a brother-in-law (szwagier) or professional associates like an advisor (doradca), you can connect clauses using the relative pronoun który (who, whom, which, whose).
When you connect clauses with który, it follows two strict rules:
- Its gender matches the noun it refers to in the main clause.
- Its case depends entirely on its role in the relative clause.
który declines like an adjective. In the Genitive, Dative, and Instrumental cases, the singular forms are:
| Case | Masculine / Neuter | Feminine |
|---|
| Genitive | którego | której |
| Dative | któremu | której |
| Instrumental | którym | którą |
(Note: The feminine Genitive and Dative forms are identical).
Instrumental: "z którym" and "z którą"
Use którym or którą if the relative clause uses a preposition like z (with) or a verb requiring the Instrumental case:
Some masculine professions end in -a (like zastępca or doradca). While the noun itself takes a feminine-looking ending in the Instrumental case (z zastępcą), it is grammatically masculine and requires the masculine pronoun którym:
Genitive: "którego" and "której"
Use the Genitive forms to express possession ("whose"), after prepositions like od (from), or with verbs requiring the Genitive case (like szukać - to look for):
Dative: "któremu" and "której"
Use the Dative forms for the indirect object of the relative clause ("to whom" or "for whom"). You will need this with verbs like pomagać (to help), ufać (to trust), or kupić (to buy for someone).