This is the 7602nd most frequent Polish word.
lasem
"Lasem" means "forest" in the instrumental case of the Polish noun "las."
'Lasem' is used in its instrumental form to indicate the means or place of movement.
Chodzę przez lasem.
I walk through the forest.
Here 'lasem' is in instrumental case, emphasizing the area where the strolling happens.
Spaceruję lasem każdego dnia.
I stroll through the forest every day.
'Lasem' is again instrumental, depicting the surrounding area through which the road leads.