1. A tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways
   "Oxygen diffuses into the bloodstream through the walls of alveoli";
   - air sac, air cell
    
2. A bony socket in the alveolar ridge that holds a tooth
   "After the tooth extraction, the dentist carefully cleaned the alveolus";
   - tooth socket

Derived forms: alveoli

Type of: sac, socket

Part of: alveolar process, alveolar ridge, gum ridge, lung

Encyclopedia: Alveolus