n :  a system that provides all or some of the items (as oxygen, food, water, and disposition of carbon dioxide and body wastes) necessary for maintaining life or health: as  a  :  one used to maintain the health of a person or animal in outer space, underwater, or in a mine  b  :  one used to maintain the life of an injured or ill person unable to maintain certain physiological processes without artificial support .
 
 
 
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