alveolus /alvē″ələs/ pl. alveoli [L, alveolus, little hollow] , 1. a small outpouching along the walls of the alveolar sacs through which gas exchange between alveolar air and pulmonary capillary blood takes place. Also called acinus, pulmonary alveolus. 2. a tooth socket. See also dental alveolus. −alveolar, adj.
