Greetings everyone, I am a bit confused by the occasional use of adjectival endings for certain types of nouns in the accusative case (biernik) znam twojego brata I know your brother. OK znam twojego znajomego I know your acquaintance (male) Here Znajomy takes an adjectival ending but why? I know that narzeczony and krewny are similar. to jest Jan Zieliński that is Jan Zielinski znam Jana Zielińskiego I know Jan Zielinski similarly why is this surname taking an adjectival ending? znam Jana Nowaka I know Jan Novak znam Ewę Zielińską I know Eva Zielinska Ewę is of course the usual feminine accusative form but this surname behaves like an adjective. znam Ewę Nowak I know Eva Novak Are there any rules of thumb to help the beginner know where to expect these adjectival ending on some nouns and at least some personal nouns. Thanks Phil.