Plain English Meaning
A flying craft that floats in the air because it is filled with a gas lighter than the surrounding air, and has engines and steering so the pilot can drive it where they want to go.
Full Definition
A power-driven, lighter-than-air aircraft that can be steered. It uses a gas (typically helium) inside a large envelope to provide lift, and engines with control surfaces to provide thrust and directional control.
Context Anchor
Seen when FAA material distinguishes different kinds of aircraft, especially lighter-than-air aircraft such as balloons and airships.
Derivation
A simple combination of 'air' and 'ship.' Early designers thought of these craft as ships that sailed through the air rather than across water — they were navigated, steered, and crewed in a similar way.