Plain English Meaning

A fast-spinning wheel that wants to keep pointing the same way no matter how the aircraft moves around it. Because it stays steady, instruments can use it as a fixed reference to show pitch, bank, heading, or turn rate.

Full Definition

A spinning wheel or disc mounted so that its axis is free to rotate, which resists changes to the direction it is pointing. This resistance, combined with a related behavior called precession, allows the spinning element to serve as a stable reference for measuring an aircraft's attitude, heading, or rate of turn.

Context Anchor

Seen in gyroscopic flight instruments such as the attitude indicator, heading indicator, and turn coordinator.