(medicine) An abnormal deficiency in the concentration of oxygen in the blood, be it the partial pressure of oxygen (mm Hg), the content of oxygen (ml oxygen per dl of blood) or the per cent saturation of the blood's hemoglobin, singly or in combination.
1984. Alan Morris, Richard Kanner, Robert Crapo, Reed Gardner, Clinical Pulmonary Function Testing. A manual of uniform laboratory procedures, 2nd edition:
The most profound abnormality determines the oxygen deficiency category ... of hypoxemia.