noun

• Loss of consciousness due to the interruption of breathing and consequent anoxia.
• Loss of consciousness due to the body's inability to deliver oxygen to its tissues, either by the breathing of air lacking oxygen or by the inability of the blood to carry oxygen.
• (medicine, obsolete) A condition in which an extreme decrease in the concentration of oxygen in the body leads to loss of consciousness or death. Replaced in the mid-20th century by the more specific terms anoxia, hypoxia, hypoxemia and hypercapnia.