This is the 7485th most frequent Polish word.
kowno
"Kowno" is the Polish name for the city of Kaunas in Lithuania.
Here, 'Kowno' refers to a proper noun, the name of the city Kaunas in Lithuania.
Kowno to piękne miasto na Litwie.
Kaunas is a beautiful city in Lithuania.
In this sentence, 'Kownie' is a locative case form of the noun 'Kowno,' indicating that the action is taking place within the city.
Moja babcia mieszka w Kownie od wielu lat.
My grandmother has lived in Kaunas for many years.
Here, 'Kowno' is used in its nominative form, naming the city Kaunas in the context of travels.