pneumatocele
noun
pneu·ma·to·cele
| \ ˈn(y)ü-mət-ō-ˌsēl
, n(y)u̇-ˈmat-ə-
\
, n(y)u̇-ˈmat-ə-
\
Medical Definition of pneumatocele
: a gas-filled cavity or sac occurring especially in the lung