IRGENDJemandes
Irgendjemandes is the genitive form of the German indefinite pronoun irgendjemand, used to indicate ownership by an unspecified person. It functions as a possessive modifier and can attach to a noun in a variety of positions, for example irg endjemandes Auto or das Auto irgendjemandes.
Form and usage: The standard declension of irgendjemand yields: nominative irgendjemand, genitive irgendjemandes, dative irgendjemandem, accusative
Nuance and register: Irgendjemandes conveys vagueness about the owner and can shift emphasis toward the object
Examples: Ich habe irgendjemandes Schlüssel gefunden. Das ist irgendjemandes Auto vor dem Haus. Das könnte das
See also: indefinite pronouns in German, possessive constructions, genitive usage in German.