Plain English Meaning
Your blood has plenty of oxygen, but it isn't moving properly to where the body needs it, so cells start to suffer.
Full Definition
A form of hypoxia in which the blood is properly oxygenated but fails to circulate adequately to the body's tissues, so oxygen is not delivered where it is needed. Causes include reduced cardiac output, restricted blood flow from prolonged G-forces, cold temperatures cutting off circulation to extremities, or a constricted artery.
Context Anchor
Seen in aeromedical discussions of hypoxia, especially when learning how circulation problems or strong maneuvering forces can affect a pilot’s brain and vision.
Derivation
From the Latin 'stagnare', meaning 'to stand still' (as water in a stagnant pond). The name points to the cause: blood that isn't moving freely, even though it carries enough oxygen.