“+ noun
Etymology: International Scientific Vocabulary oxy- (II) + hemoglobin
: the bright red crystallizable pigment in the red blood cells chiefly of arterial blood that is formed in the lungs or gills by the combination of hemoglobin with oxygen in the ratio of one molecule of oxygen to each atom of iron in the hemoglobin without oxidation of the iron to the ferric state and that releases its oxygen to the tissues — symbol HbO 2