1. a small cavity or pit, especially one of the tiny air sacs in the lungs where gas exchange occurs
Usage: anatomy; plural: alveoli
2. a small socket in the jawbone that holds the root of a tooth
Usage: anatomy; dentistry; plural: alveoli
3. a small cavity or depression in a surface, such as in honeycomb or plant tissue
Usage: biology; plural: alveoli

Examples

• Oxygen enters the bloodstream through the alveoli in the lungs.
• Each alveolus is surrounded by tiny blood vessels called capillaries.
• The tooth is anchored in the alveolus of the jawbone.
• Damage to the alveoli can reduce the lungs' ability to absorb oxygen.
• Honeycomb is made up of many small hexagonal alveoli.
• Alveoli are essential structures for respiration in mammals.