Source : Webster's Revised Unabridged Dictionary (1913)

Lung \Lung\, n. [OE. lunge, AS. lunge, pl. lungen; akin to D.
   long, G. lunge, Icel. & Sw. lunga, Dan. lunge, all prob. from
   the root of E. light. ? See {Light} not heavy.] (Anat.)
   An organ for a["e]rial respiration; -- commonly in the
   plural.

         My lungs began to crow like chanticleer. --Shak.

Source : WordNet®

lung
     n : either of two saclike respiratory organs in the chest of
         vertebrates; serves to remove carbon dioxide and provide
         oxygen to the blood