Alveolus (/ælˈviːələs/; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit.

• Pulmonary alveolus, an air sac in the lungs
  • Alveolar cell or pneumocyte
  • Alveolar duct
  • Alveolar macrophage
• Mammary alveolus, a milk sac in the mammary glands
• Alveolar gland
• Dental alveolus, also known as "tooth socket", a socket in the jaw that holds the roots of teeth
  • Alveolar ridge, the jaw structure that contains the dental alveoli
  • Alveolar canals
  • Alveolar process
• Arteries:
  • Superior alveolar artery (disambiguation)
    • Anterior superior alveolar arteries
    • Posterior superior alveolar artery
  • Inferior alveolar artery
• Nerves:
  • Anterior superior alveolar nerve
  • Middle superior alveolar nerve
  • Inferior alveolar nerve

• Surface cavities or pits, such as on the stem of Myrmecodia species
• Pits on honeycombed surfaces such as receptacles of many angiosperms
• Pits on the fruiting bodies of fungi such as Boletus or the ascocarps of fungi such as typical ascomycetes
• Pits on the valves of the tests of many diatoms
• Membrane supporting vesicles of the alveolates

• Alveolar consonant, a linguistic vocalization which involves placing one's tongue against the alveolar ridge
• Alveolar stop

• The dictionary definition of alveolus at Wiktionary
• The dictionary definition of alveolar at Wiktionary
• Alveolar soft part sarcoma, a very rare type of soft-tissue sarcoma,
• Acinus, considered by some (but not all) sources to be synonymous with Alveolus