Definition
A spinning rotor mounted so that its axis is free to tilt in one or more directions. Once spinning at high speed, the rotor resists changes to the direction of its spin axis and provides a stable reference that gyroscopic flight instruments use to sense aircraft attitude, heading, or rate of turn.
Plain English
A fast-spinning wheel inside an instrument that holds its position in space, giving the instrument a steady reference to measure how the aircraft is moving.
Context Anchor
Seen in discussions of gyroscopic flight instruments, especially the attitude indicator, heading indicator, and turn coordinator.
Derivation
From the Greek 'gyros' meaning 'circle' or 'ring.' The name points to the spinning, circular motion that gives the device its stability.
Why Pilots Care
Gyroscopic instruments supply the stable attitude and heading references pilots need when visual cues outside the cockpit are lost or unreliable.
Analogy
Like a spinning top: while it is spinning fast, it stays upright and resists being pushed over. A gyro uses that same property to hold a steady reference inside an instrument.
Intuition Check
In aviation, gyro does not mean the food. It is short for gyroscope, a spinning device used as a steady reference in flight instruments.
Example Sentence 1
After starting the engine, the pilot waited a few minutes for the gyros to spin up before relying on the attitude indicator.
Example Sentence 2
After several minutes of flight the heading indicator, driven by its gyro, must be realigned with the magnetic compass to correct for precession drift.