Definition
The direction the nose of the aircraft is pointed, measured in degrees clockwise from magnetic north. Magnetic heading is true heading corrected for magnetic variation but not for compass deviation.
Plain English
The direction your aircraft's nose is pointing, measured against magnetic north rather than the geographic North Pole.
Context Anchor
Seen in instrument flying, compass use, navigation planning, and heading instructions from air traffic control.
Derivation
From Latin 'magneticus' (relating to the magnet) and Old English 'heafod' (head, top, front). The 'heading' is literally where the head — the nose — of the aircraft is pointed, measured against the magnetic field rather than the geographic poles.
Why Pilots Care
Most cockpit instruments and compass-based navigation use magnetic north, so pilots must fly magnetic headings and then apply variation when converting to true courses on charts.
Intuition Check
Do not confuse heading with the path over the ground. Magnetic heading is where the nose is pointed; wind can make the aircraft move over the ground in a slightly different direction.
Example Sentence 1
After applying the 8 degrees east variation, the pilot rolled out on a magnetic heading of 262 degrees.
Example Sentence 2
While on the downwind leg, maintain a magnetic heading of 360 degrees until turning base.