Main Entry: lung

Pronunciation: \ˈləŋ\

Function: noun

1 a : one of the usually two compound saccular organs that constitute the basic respiratory organ of air-breathing vertebrates, that normally occupy the entire lateral parts of the thorax and consist essentially of an inverted tree of intricately branched bronchioles communicating with thin-walled terminal alveoli swathed in a network of delicate capillaries where the actual gaseous exchange of respiration takes place, and that in humans are somewhat flattened with a broad base resting against the diaphragm and have the right lung divided into three lobes and the left into two lobes

[lung illustration]

b : any of various respiratory organs of invertebrates
2 : a mechanical device for regularly introducing fresh air into and withdrawing stale air from the lungs : respirator—see iron lung

—lunged adjective