Plain English Meaning
A jet-style engine that, instead of pushing the aircraft along with exhaust, uses its turbines to spin a shaft. That shaft then turns something useful — most often a helicopter rotor.
Full Definition
A turbine engine in which most of the power produced by the expanding gases is used to drive a shaft rather than to produce thrust through the exhaust. The shaft typically drives a rotor system in a helicopter, a propeller through a reduction gearbox, or another mechanical load such as an auxiliary power unit.
Context Anchor
Seen in turbine engine discussions, especially when comparing helicopter engines with turbojet, turbofan, and turboprop engines.
Derivation
‘Turbo’ comes from the Latin turbo, meaning a spinning or whirling thing — the same root behind ‘turbine.’ ‘Shaft’ is the rotating rod that carries the power out of the engine. So the name simply describes what the engine does: a turbine that delivers its power through a shaft.
Why Pilots Care
Turboshaft engines supply the high torque at moderate RPM needed to turn helicopter rotors efficiently, making vertical flight practical with good power-to-weight performance.
Intuition Check
Do not read “turboshaft” as “a turbocharger on a shaft.” Here it means a complete turbine engine whose main job is to turn an output shaft.
Example Sentence 1
The helicopter is powered by a single turboshaft engine driving the main and tail rotors through a reduction gearbox.
Example Sentence 2
During preflight, the pilot checks the turboshaft oil level and N1 and N2 gauges before starting.