Adding what word to the end of a cloud name indicates precipitation?

Adding "nimbus" or "nimbo" to a cloud name indicates precipitation is falling or may fall from the cloud. There are many types of clouds, but only certain ones can produce rain. If a cumulus cloud produces rain, it is known as a cumulonimbus cloud.

Nimbostratus clouds are the low-hanging rain clouds that are usually seen on an overcast day. They tend to produce light rain and their presence indicates the stratus layer is strengthening and thickening.

Cumulonimbus clouds are the main rain producers. They appear large and puffy and extend high into the atmosphere. Unlike the light rain produced by nimbostratus clouds, cumulonimbus produce the heavy rains associated with severe weather. Some cumulonimbus clouds can produce wind, lightning, thunder, and tornadoes.

The word "nimbus" is Latin for "cloud" or "halo". It was first used by Luke Howard, a British amateur meteorologist, in 1802. Howard published his 'Essay on the Modification of Clouds' in 1803.