Plain English Meaning
Everyday civilian flying that isn't an airline flight or a military flight. If you're learning to fly, flying yourself somewhere, or flying for a small business, that's general aviation.
Full Definition
All civil aviation activity other than scheduled airline operations and military flying. It includes private flying, flight training, business and corporate flights, agricultural work, aerial survey, charter, medical flights, and most personal aircraft use.
Context Anchor
Seen in FAA training material when guidance applies mainly to non-airline pilots and aircraft, including stabilized approach discussions.
Derivation
General' here means 'covering everything else.' After airline (scheduled commercial) and military flying are set aside, what remains is the 'general' category of activity.