the.com/hypoxia

means A dangerous shortfall of oxygen reaching the body's tissues, impairing how they function.

from Built from Greek roots: 'hypo-' (under, below) plus 'oxy-' from oxygen itself — a 20th-century coinage, part of a family of medical terms (hyperoxia, anoxia) constructed to precisely label oxygen levels in the body. Oxygen's own name traces back to Greek 'oxys' (sharp, acid) plus '-gen' (producer), from an 18th-century belief that it was essential to forming acids — a guess that turned out to be wrong, though the name stuck.