In simple words, decreased of oxygen at tissue level
A condition of oxygen deficit at the tissue level. May be 1. Hypoxic hypoxia - due to defect in respiratory passage, 2. Anemic hypoxic due to lack in oxygen carrying capacity of blood, 3. Stagnant hypoxia due to interupption of blood flow to a particular organ (occlusion of an artery for example) and 4. Histotoxic hypoxia due to toxic substances that block ETC example cyanide