This is the 1064th most frequent Polish word.
dziwnego
The Polish word "dziwnego" means "strange" or "weird" (genitive or accusative singular form of "dziwny").
The word "dziwnego" is used here as an adjective in genitive case modifiying "nic" to describe something unusual.
Nie widziałem nic dziwnego w jego zachowaniu.
I didn't see anything strange in his behavior.
Here,"dziwnego" serves as the adjective describing the element "coś" (something) in genitive case, emphasizing an unusual detail.
Czy jest coś dziwnego w tej sytuacji?
Is there something strange about this situation?
In this case, "dziwnego" modifies "czymś" (something) in instrumental case, indicating the peculiarity of the subject in question.