or chiefly Brit  met*hae*mo*glo*bin  n :  a soluble brown crystalline basic blood pigment that is found in normal blood in much smaller amounts than hemoglobin, that is formed from blood, hemoglobin, or oxyhemoglobin by oxidation, and that differs from hemoglobin in containing ferric iron and in being unable to combine reversibly with molecular oxygen - called also ferrihemoglobin  .
 
 
 
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