Thundercloud (noun)

1. A dense cloud that is associated with thunder and lightning.
2. A cloud of a dark, ominous appearance that often presages a thunderstorm.

Origin:

From thunder + cloud.

Examples:

1. The thunderclouds started to gather on the horizon, signaling an approaching storm.
2. The dark and brooding thundercloud filled the sky, making it seem as though the world was about to end.
3. The thundercloud was a beautiful and awe-inspiring sight, with its lightning flashing and thunder rumbling.
4. The thundercloud provided a dramatic backdrop for the outdoor concert.
5. The thundercloud was a sign of a fierce and powerful storm that was sure to come.