Plain English Meaning
A pump driven by the engine that pushes extra air into the cylinders so the engine can make more power, especially up high where the air is thin.
Full Definition
A mechanically driven air pump used on a reciprocating aircraft engine to compress the air entering the cylinders. By forcing in a denser charge of air, the blower allows the engine to produce more power than it could under normal atmospheric induction, and to maintain power at higher altitudes where the air is thinner. The term is most often associated with gear-driven superchargers, but is also used loosely for the impeller section of a supercharger or for any engine-driven air pump that pressurizes the induction system.
Context Anchor
Seen in aircraft engine, supercharger, and high-power piston engine discussions.
Derivation
From the everyday word for something that blows air. The name stuck because the device literally blows pressurized air into the engine's intake.
Why Pilots Care
Allows the engine to maintain power as altitude increases, improving climb performance and high-altitude cruise capability.
Intuition Check
Do not read “blower” here as just a cabin fan or a heater fan. In engine context, it usually means a compressor that pushes extra air into the engine for power.
Example Sentence 1
At higher altitudes the pilot shifted into high blower to keep the engine producing rated power.