A nimbus cloud doesn't have a specific shape. The word "nimbus" actually means "rain cloud" and is used as a suffix to indicate that the cloud is associated with precipitation. So, you might have a cumulonimbus cloud (thunderstorm), stratocumulus nimbus (rain), or altostratus nimbus (rain).

Each of these cloud types has a different shape:

* Cumulonimbus: Towering, anvil-shaped clouds.

* Stratocumulus nimbus: Gray, lumpy clouds covering most of the sky.

* Altostratus nimbus: Grayish sheet clouds, sometimes with a fibrous appearance.

So, the shape of a nimbus cloud depends on the specific type of cloud it is.