How to say "bladder" in Japanese

• 気胞きほう
  nounA technical term for a gas-filled vesicle or sac, used in scientific contexts. It is not the word for the urinary bladder, and it is a less common choice for 'bladder' generally.
• 空気袋くうきぶくろ
  nounA plainly descriptive word for a bag of air: an air sac or air bladder. Figuratively it can mean a windbag, someone full of hot air, and it does not refer to the urinary bladder.
• 膀胱ぼうこう
  nounThe word for the urinary bladder, the organ that stores urine. Use it whenever 'bladder' refers to that organ rather than to a sac of air or a vesicle.

All three are less common renderings: use 膀胱 for the urinary bladder, 気胞 for a gas-filled vesicle, and 空気袋 for a literal bag of air or, figuratively, a windbag.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 気胞きほうbladder
• 空気袋くうきぶくろair sac
• 膀胱ぼうこうurinary bladder