This is the 7473rd most frequent Polish word.
kosakowie
"Kosakowie" in Polish refers to "Cossacks," a group of East Slavic people known for their military traditions and self-governing communities.
Here, 'kosakowie' is used as a nominative plural form surname to refer to a family collectively.
Kosakowie mieszkają w dużym, białym domu na obrzeżach miasta.
The Kosak family lives in a big, white house on the outskirts of the city.
In this sentence, 'Kosaków' is in the accusative plural case, indicating the group of people being visited.
W zeszły weekend odwiedziliśmy Kosaków, którzy zaprosili nas na grilla.
Last weekend, we visited the Kosaks, who invited us for a barbecue.
The word 'Kosaków' here is in the genitive plural case, used to denote possession or relation.