air sac

noun

1. a sac containing air.
2. alveolus ( def 2 ).
3. any of certain cavities in a bird's body connected with the lungs.
4. a saclike dilation of the wall of a trachea in many insects.

air sac

noun

1. any of the membranous air-filled extensions of the lungs of birds, which increase the efficiency of gaseous exchange in the lungs
2. any of the thin-walled extensions of the tracheae of insects having a similar function

air sac

1. An air-filled space in the body of a bird that forms a connection between the lungs and bone cavities and aids in breathing and temperature regulation.
2. See alveolus
3. A saclike enlargement in the trachea of an insect.
4. A baglike piece of skin or tissue below the jaw of certain animals, such as the bullfrog and orangutan, that can be inflated to increase sound production.

Word History and Origins

Origin of air sac¹

First recorded in 1820–30

Example Sentences

A micro CT scan - that produces 3D images - revealed the contents of the egg, complete with the air sac.

From BBC

The study also found that the children are missing half of their alveolar macrophages, which are located in the air sacs of the lungs.

From Science Daily

Conversely, epithelial cells, which line the air sacs of the lungs and are the precursors to lung adenocarcinomas, grow excessively in response to mutated EGFR.

From Science Daily

They drew inspiration from the architecture of the human lungs, which contain spherical "air sacs" called alveoli that enable a high interaction rate with blood within a short time.

From Science Daily

Within the lungs, oxygen is absorbed and carbon dioxide released via air sacs called alveoli.

From Science Daily