alveolus
noun /ælˈviːələs/, /ˌælviˈəʊləs/
/ælˈviːələs/
(plural alveoli
(anatomy) /ælˈviːəlaɪ/, /ælˈviːəliː/, /ˌælviˈəʊlaɪ/, /ˌælviˈəʊliː/
/ælˈviːəlaɪ/, /ælˈviːəliː/
)- one of the many small spaces in each lung where gases can pass into or out of the bloodWord Originlate 17th cent.: from Latin, ‘small cavity’, diminutive of alveus.