brooding
Definitions
Showing deep unhappiness of thought; appearing dark, menacing, or threatening.
Engaged in or showing deep, serious, and often melancholy thought.
Sitting on eggs to hatch them.
Examples
The brooding clouds on the horizon suggested that a severe thunderstorm was approaching.
He sat in the corner of the room, brooding over the mistakes he had made during the presentation.
Synonyms
pensive melancholy moody contemplative morose somber wistful