This is the 6482nd most frequent Polish word.
cień
"Shadow" or "shade."
Here, 'cień' is used in the context of shade, referring to the sheltered, cool area caused by the tree blocking sunlight.
Cień drzewa zapewniał chłód w upalny dzień.
The shade of the tree provided coolness on a hot day.
In this sentence, 'cień' symbolizes an abstract shadow, signifying the metaphorical presence of sadness.
Jego twarz pokrył cień smutku, gdy usłyszał wiadomość.
His face was covered by a shadow of sadness when he heard the news.
Here, 'cień' literally means the shadow cast by his body blocking the light source, visible on the ground behind him.