You searched for: “aerostat
aerostat (s) (noun), aerostats (pl)
1. A dirigible, balloon, or other aircraft that is lifted and sustained by virtue of one or more containers filled with a gas lighter than air.
2. Any of a proposed system of satellites for use in air traffic control and maritime navigation.
3. In biology, an air sac in an insect body or in the bones of a birds.
4. Etymology: from aero, [nautical] + sat [ellite].