air sac; gasbag; balloon
Meanings
2 senses · 7 examplesnoun
air sac (in avian respiratory system)
Anatomical structures in birds that enable efficient gas exchange and reduce body density for flight. They extend into bones and body cavities.
The air sacs of birds are distributed throughout the body cavity.
Some air sacs are located inside the bones, which can reduce the bird's weight.
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Air sacs help birds perform double breathing during flight.
noun
gasbag; inflatable rubber bag; airbag (engineering)
Used in aviation for high-altitude balloons and airships. In modern usage, also refers to automobile airbags (安全气囊).
The gasbags of high-altitude balloons must be able to withstand extreme pressure changes.
The airship's gasbags are filled with helium, which is lighter than air.
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The car's airbag inflates and deploys rapidly during a collision.
This type of rubber airbag is often used for underwater salvage operations.