'ballonet' originates from French, specifically the word 'ballonnet', where 'ballon' meant 'balloon' and the diminutive suffix '-et' meant 'small'.

'ballonet' entered English in the late 19th century from French 'ballonnet' (a diminutive of 'ballon') and was adopted into aeronautical terminology.

Initially it meant 'a small balloon'; over time it evolved to the specific meaning 'an internal air bag inside an airship used for trimming and pressure control'.