Noun
One of the spaces in different parts of the bodies of birds, which are filled with air and connected with the air passages of the lungs; an air cell.
Source: Webster's dictionaryIn most species, the sound is produced by expelling air from the lungs over the vocal cords into an air sac or sacs in the throat or at the corner of the mouth. Source: Internet
Evaporation can be assessed by candling, to view the size of the air sac, or by measuring weight loss. Source: Internet
The presence of a subcutaneous air sac system in at least some pterodactyloids would have further reduced the density of the living animal. Source: Internet
The syrinx depends on the air sac system in birds to function; specifically, it requires the presence of a clavicular air sac near the wishbone or collar bone. Source: Internet
The walrus has an air sac under its throat which acts like a floatation bubble and allows it to bob vertically in the water and sleep. Source: Internet
Upon inhalation, 75% of the fresh air bypasses the lungs and flows directly into a posterior air sac which extends from the lungs and connects with air spaces in the bones and fills them with air. Source: Internet