air cell

1. A terminal dilation of the bronchiole in lungs or similar organs where gas exchange occurs.

   a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways

2. Spaces that contain air in the bones of the skull.

3. A prechamber in an indirect injection internal combustion engine.

4. An electrochemical cell that uses air as a terminal, such as the metal-air electrochemical cell.

5. Used other than figuratively or idiomatically: see air cell.

   An air cell formed as the egg cooled and dried

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