In medicine, the absence or almost complete absence of oxygen: One kind of anoxia can cause death which results from strangulation when an animal cannot breath in any oxygen from the air.

The absence or deficiency of oxygen from the body's gases, blood, or tissues: Ed was told that if his anoxia continues for more than four to six minutes, he could have irreversible brain damage.

Lack of oxygen to the brain: Cerebral anoxia often causes sensory distortions and hallucinations and sometimes cerebral anoxia is used to explain features of the near-death experience.

A near-death experience (NDE) consists of experiences of people after they have been pronounced clinically dead, or who have been very close to death.

Typical features of the near-death experiences are an OBE (Out of Body Experience), a fully conscious experience in which the person's center of awareness appears to be outside the physical body, a life review, a tunnel experience, a light, coming to a boundary (marking death), seeing dead friends, and relatives, experiencing a loving or divine presence, and making a choice (or being told) to return.

Occasionally near-death experiences can be frightening and distressing, and often have profound effects on the person's later life.