- A sac or bladder full of air in an animal or plant; also an air hole in a casting.
- An air sac, sometimes double or variously lobed, in the visceral cavity of many fishes. It originates in the same way as the lungs of air-breathing vertebrates, and in the adult may retain a tubular connection with the pharynx or esophagus.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). air bladder. Retrieved September 21, 2026, from http://smartdefine.org/air_bladder/definitions/1971964 |
| Chicago | Webster's. 2011. "air bladder" http://smartdefine.org/air_bladder/definitions/1971964 (accessed September 21, 2026). |
| Harvard | Webster's 2011, air bladder, Smart Define, viewed 21 September, 2026, <http://smartdefine.org/air_bladder/definitions/1971964>. |
| MLA | Webster's. "air bladder" 27 May 2011. Web. 21 September 2026. <http://smartdefine.org/air_bladder/definitions/1971964> |