Definition
An increase in pressure above ambient or normal levels, typically applied to the air or fuel/air mixture entering an engine, or to a hydraulic, fuel, or assist system. In powerplant context, boost most commonly refers to manifold pressure raised above atmospheric by a supercharger or turbocharger, or to a pump that raises fuel pressure before it reaches the engine-driven pump.
Plain English
Boost means giving something extra pressure on purpose — pushing more air into the engine, or pushing fuel along with more force than it would have on its own.
Context Anchor
Seen in engine power, turbocharger, supercharger, and manifold pressure discussions, especially during takeoff, climb, and engine maintenance checks.
Derivation
From the everyday English word 'boost,' meaning to lift or push up. In aviation it keeps that plain meaning — something is being lifted above its normal level, usually pressure.
Why Pilots Care
Boost lets the engine keep producing rated power at higher altitudes where thinner air would otherwise cause power loss.
Intuition Check
Boost does not just mean “more power” in a general sense. Here it means extra air pressure being supplied to the engine intake.
Example Sentence 1
The turbocharger provides boost to the induction system, allowing the engine to maintain sea-level power at altitude.
Example Sentence 2
At 8000 feet the turbo maintained 25 inches of boost to keep takeoff power available.