Definition
Describing a device, typically a supercharger or turbocharger, that compresses induction air in two or more sequential steps, with each stage feeding the next to achieve a higher overall pressure than a single stage could produce.
Plain English
Built with more than one compression step, where air is squeezed once, then squeezed again, and sometimes again, to pack more of it into the engine.
Context Anchor
Seen in discussions of superchargers and induction systems, especially where an engine is designed to maintain power as altitude increases.
Derivation
From 'multi-' (Latin multus, meaning many) and 'stage' (a step or level in a process). In an induction system, each 'stage' is one compression step, so 'multistage' simply means 'multiple compression steps in series.'
Why Pilots Care
Higher manifold pressure at altitude improves engine performance and allows flight above the service ceiling of normally aspirated engines.
Intuition Check
Do not read “stage” here as a phase of training or a level of progress. In this context, a stage is a separate section that does part of the air-pressure increase.
Example Sentence 1
The aircraft's multistage supercharger allowed the engine to hold full rated power well above 20,000 feet.
Example Sentence 2
During preflight the mechanic inspected each stage of the multistage compressor for signs of wear or foreign object damage.