který

Který is a word in Czech that functions as both an interrogative determiner and a relative pronoun. As an interrogative determiner, it means "which" and is used to ask about a choice from a set of possibilities, for example: Který dům je tvůj? (Which house is yours?)

In its role as a relative pronoun, který introduces a relative clause that describes a noun mentioned earlier, roughly corresponding to "which" or "that" in English. For example: Muž, který přišel, je učitel. (The man who/that came is a teacher.) Žena, která přišla, je lékařka. Dítě, které spalo, se probudilo. These examples show how kýstr forms adapt to the noun they modify.

Který must agree with its antecedent in gender, number, and case, so its form changes within the relative clause. In general terms, it has distinct forms for masculine, feminine, and neuter nouns, and these forms also vary by function in the clause (subject, object, etc.). For masculine singular nominative it appears as který; for feminine singular nominative it appears as která; for neuter singular nominative it appears as které. In other cases the endings shift to reflect Czech grammar.

Který is common in everyday Czech; there are more literary alternatives such as jenž and jejž, which appear in older or formal styles. The word co is used to refer to whole clauses or concepts rather than to a noun phrase.

Etymology traces to a common Slavic root meaning "which," related to similar words in other Slavic languages.