Definition
A spinning rotor mounted in gimbals that resists changes to the orientation of its spin axis. This property — rigidity in space — allows it to hold a steady reference direction while the aircraft moves around it, which is why it forms the heart of instruments such as the attitude indicator, heading indicator, and turn coordinator.
Plain English
A small, fast-spinning wheel that wants to keep pointing the same way no matter how the aircraft tilts or turns. Instruments use that steady-pointing behavior to show pitch, bank, and heading.
Context Anchor
Seen in aircraft instrument system descriptions, especially for instruments that show heading, turning, or the airplane’s position relative to the horizon.
Derivation
From the Greek gyros, meaning 'circle' or 'turn.' The name fits: a gyro's usefulness comes entirely from the steady spinning motion of its rotor.
Why Pilots Care
Gyro instruments give reliable attitude and heading information when outside visual references are lost, allowing safe flight in clouds or at night.
Analogy
Like a spinning top on a table — once it's spinning fast, it stays upright and resists being pushed over. A gyro uses that same stubborn behavior to hold a reference the instruments can read.
Intuition Check
A gyro is not just any spinning part. In aviation, it means a spinning device used as a stable reference for an instrument or system.
Example Sentence 1
When the vacuum pump failed, the attitude indicator's gyro spun down and the instrument slowly tilted off level.
Example Sentence 2
After starting the engine, the heading indicator gyro was allowed to spin up before the aircraft taxied for takeoff.