This is the 1456th most frequent Russian word.
категорий
"Категорий" is the genitive plural form of "категория," meaning "categories."
The word 'категорий' is in the genitive plural form, indicating multiple groups or classifications of books.
Существуют разные категории книг на рынке.
There are different categories of books on the market.
The word 'категорий' appears in the singular genitive form as part of the possessive description of 'премиум-класса'.
Этот продукт относится к категории премиум-класса.
This product belongs to the premium category.
The word 'категорий' is used in the genitive plural form to denote various types or classes of problems that were discussed.