either of two saclike respiratory organs in the chest of vertebrates; serves to remove carbon dioxide and provide oxygen to the blood
"The doctor listened carefully to my lungs with a stethoscope before diagnosing the infection."
A biological organ of vertebrates that controls breathing and oxygenates the blood.
"After running up the steep hill, she felt her lungs burning as they worked hard to pull in enough fresh air."
In plain English: A lung is a large organ inside your chest that takes oxygen from the air you breathe and sends it into your blood.
"The doctor told him to stop smoking to protect his lungs."
Usage: Use lung to refer specifically to the vital organ in your chest responsible for breathing and filtering oxygen into your bloodstream. Do not use it to describe other body parts like the liver or lungs unless you are explicitly talking about respiration.
A surname.
"The Lung family has been running the local bakery for three generations."
The word "lung" comes from Old English lungen, which originally meant the light organ. It traveled into modern English with that same meaning, likely because early observers thought the lungs were filled with air and therefore very light.