Heading indicator
A gyroscopic flight instrument that gives the pilot an indication of the heading of the aircraft.
Aviation Maintenance Technician Handbook — Airframe, p. G-18
Also defined in 1 more source
An instrument which senses airplane movement and displays heading based on a 360° azimuth, with the final zero omitted. The heading indicator, also called a directional gyro (DG), is fundamentally a mechanical instrument designed to facilitate the use of the magnetic compass. The heading indicator is not affected by the forces that make the magnetic compass difficult to interpret.