This is the 5646th most frequent Polish word.
wirusów
"Virusów" means "of viruses" in English.
Here, 'wirusów' is the plural, genitive case form of 'wirus', used to describe the quantity (many) of computer viruses.
Komputer został zainfekowany przez wiele wirusów.
The computer got infected by many viruses.
In this sentence, 'wirusów' is incorrectly used; the correct form should be 'wirusami' (instrumental case for 'wirus'), demonstrating an educational fix.
Naukowcy opracowali nowe metody walki z wirusów.
Scientists have developed new methods to combat viruses.
The word 'wirusów' identifies 'viruses' and is in the plural, genitive case, emphasizing types/categories.