also: くうきふくろ
noun
air sac; bladder; air bag; windbag
Refers to any flexible container or biological structure that holds air, such as an inflatable bag, a swim bladder, or an anatomical air sac.
魚の空気袋は浮力を調節する役割がある。
The fish's air bladder has the role of adjusting buoyancy.
このおもちゃの空気袋に空気を入れてください。
Please inflate this toy's air bag.
Compound of 空気 (air) and 袋 (bag, sack). The reading くうきぶくろ uses rendaku voicing on ふくろ, while くうきふくろ retains the unvoiced form.