This is the 7936th most frequent Polish word.
mroczy
The Polish word "mroczy" means "gloomy" or "dark" in English.
Here, 'mroczy' is used as an adjective describing the sky being gloomy and dim, a metaphorical extension of darkness.
Niebo było mroczy, zwiastując nadchodzącą burzę.
The sky was gloomy, signaling an upcoming storm.
In this sentence, 'mroczy' is used figuratively to describe the tone of the ending, being dark and ominous.
Tę historii mroczy koniec zawsze mnie przerażał.
The grim ending of this story always frightened me.
Here, 'mroczy' is applied to describe his facial expression as being dark or somber, indicating mood or emotion.