Definition
A direction-indicating instrument that uses a gyroscope to maintain a stable heading reference, aligned to a fixed direction such as true north or a heading set by the pilot, independent of the Earth's magnetic field.
Plain English
An instrument that shows your heading using a spinning gyroscope instead of a magnet, so it stays steady and isn't fooled by the things that disturb a magnetic compass.
Context Anchor
Seen in instrument navigation discussions, especially when an ADF bearing pointer is shown on an RMI instead of on a fixed compass card.
Derivation
From 'gyro' (Greek 'gyros', meaning a turn or circle) and 'compass' (a direction-finding instrument). The name reflects that direction is held by a spinning wheel rather than by magnetism.
Why Pilots Care
It supplies a stable true heading reference that remains reliable when magnetic compasses are disturbed by aircraft systems or local magnetic fields.
Intuition Check
Do not read “gyrocompass” as just another name for the magnetic compass. A gyrocompass uses a spinning gyro to hold or display heading; a magnetic compass points using Earth’s magnetic field.
Example Sentence 1
Before takeoff, the pilot aligned the gyrocompass with the magnetic compass so the heading indicator would read correctly in flight.
Example Sentence 2
Even after a series of turns, the gyrocompass continued to show accurate direction without swinging.