Definition
Relating to or operated by air or other gas under pressure. In gas turbine engines, pneumatic systems use compressed air bled from the engine compressor to power components such as engine starters, anti-ice systems, cabin pressurization, and air-driven instruments.
Plain English
Powered by pressurized air. In a turbine engine, high-pressure air taken from inside the engine is piped around the aircraft to run things that need an air supply.
Context Anchor
Seen in gas turbine engine discussions when a system uses pressurized air for tasks such as starting the engine or moving air-operated parts.
Derivation
From the Greek 'pneuma,' meaning breath or air. The same root appears in 'pneumonia' (a lung condition). It helps because pneumatic systems literally run on moving air -- the engine 'breathes out' compressed air to power other parts of the aircraft.
Why Pilots Care
Pneumatic starters and controls give reliable engine starting and anti-icing without depending on electrical power.
Analogy
A bicycle tire is not powered by air, but it shows the basic idea: air under pressure can hold shape and create force. A pneumatic aircraft system uses that kind of pressure to move or operate something.
Intuition Check
Pneumatic does not mean automatic or electronic. Here it means the system does its work with air pressure.
Example Sentence 1
The turbine engine's pneumatic starter uses high-pressure air to spin the compressor up to starting speed.
Example Sentence 2
Bleed air from the compressor feeds the pneumatic anti-icing valves on the wing leading edges.