noun, feminineplural: rozières
A hybrid balloon with two lift gas chambers, an upper chamber filled with hydrogen, and a lower chamber that is a hot air balloon.; Rozier balloon, Rozier, Roziere balloon, Roziere, hybrid balloon: A balloon buoyed by a lifting gas that does not need heating, and has additional buoyancy from a hot air balloon element.
Rozier + -ière. Named after Jean-François Pilâtre de Rozier, who created the first such hybrid hydrogen-hot-air balloon.