(1) A condition in which oxygen is completely absent or depleted.
(2) Severe hypoxia; lack of oxygen supply, e.g. to a body organ or tissue.
Anoxia happens when a body tissue is completely deprived of oxygen. It is also observed in the environment, particularly when oxygen is depleted in a basin. This leads to denitrification wherein bacteria use nitrate of sea water as the second-best electron acceptor when oxygen is absent in water.
Word origin: an– (without) + oxy(gen) –ia.
Related forms: anoxic (adjective)
See also: hypoxia