This is the 4192nd most frequent Polish word.
czarnymi
"czarnymi" means "black" in the instrumental plural form.
The word 'czarnymi' functions as an instrumental plural adjective agreeing with the noun 'okładkami' in the instrumental case.
Książki ozdobiono czarnymi okładkami.
The books were adorned with black covers.
Here, 'czarnymi' is instrumental plural adjective describing 'kamieniami' (stones), harmonizing with its case.
Pole było pokryte czarnymi kamieniami.
The field was covered with black stones.
In this sentence, 'czarnymi' modifies 'zasłonami,' agreeing with the instrumental plural.