noun
: a system that provides all or some of the items (as oxygen, food, water, control of temperature and pressure, 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
c. : biosphere 1