'ballonet' originates from French, specifically the word 'ballonnet', where 'ballon' meant 'ball' (a diminutive form indicating a small balloon).

'ballonet' entered English from French in the 19th century with the development of ballooning and airship technology; the French 'ballonnet' (diminutive of 'ballon') became the English technical term 'ballonet'.

Initially it meant 'small balloon' or 'little ballon', but over time it became specialized to mean 'an internal airbag inside a gas balloon or airship used for pressure and buoyancy control'.