This is the 7342nd most frequent Polish word.
kasia
"Kasia" is a diminutive form of the name Katarzyna, equivalent to "Katie" or "Kate" in English.
Here, 'Kasia' is used as a proper noun referring to a person's name.
Kasia poszła na zakupy.
Kasia went shopping.
In this sentence, 'Kasia' is explained as a diminutive form of the name 'Katarzyna'.
Kasia to zdrobniała forma imienia Katarzyna.
Kasia is a diminutive form of the name Katarzyna.
In this example, 'kasia' is used colloquially, and hypothetically, as an adjective to describe something fitting or convenient.