Plain English Meaning
When you see 'nimbus' in a cloud name, it means the cloud is raining or snowing.
Full Definition
A descriptive term used in cloud naming to indicate that the cloud is producing precipitation, such as rain or snow, that reaches the ground.
Context Anchor
Seen in cloud classification, especially in names such as nimbostratus and cumulonimbus.
Derivation
From Latin 'nimbus,' meaning 'rain cloud' or 'storm.' The original Latin meaning carries straight into modern aviation use — it still flags a cloud that is actively producing precipitation.
Why Pilots Care
Nimbus clouds signal active precipitation, which can reduce visibility, create icing hazards, and affect flight planning.