anoxia anoxia anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". the terms anoxia and hypoxia are used in various contexts: anoxic waters, sea water, fresh water or groundwater that are depleted of dissolved oxygen anoxic event, when the earth's oceans become completely depleted of oxygen below the surface levels euxinic, anoxic conditions in the presence of hydrogen sulfide hypoxia (environmental), low oxygen conditions hypoxia (medical), when the body or a region of the body is deprived of adequate oxygen supply cerebral anoxia, when the brain is completely deprived of oxygen, an extreme form of cerebral hypoxia look up anoxia, anoxic, or anoxically in wiktionary, the free dictionary.