HEMOGLOBIN

n. substance in red blood cells which conveys oxygen from the lungs to body tissues

Hemoglobin, also spelled haemoglobin and abbreviated Hb, is the iron-containing oxygen-transport metalloprotein in the red blood cells of the blood in vertebrates and other animals. In mammals the protein makes up about 97% of the red cell’s dry content, and around 35% of the total content (including water). Hemoglobin transports oxygen from the lungs or gills to the rest of the body, such as to the muscles, where it releases its load of oxygen. Hemoglobin also has a variety of other gas-transport and effect-modulation duties, which vary from species to species, and may be quite diverse in invertebrates.
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Hemoglobin /he·mo·glo·bin/ the oxygen-carrying pigment of erythrocytes, formed by developing erythrocytes in the bone marrow; a hemoprotein made up [more]Hemoglobin - Community and Resources

Noun
1. a hemoprotein composed of globin and heme that gives red blood cells their characteristic color; function primarily to transport oxygen from the lungs to the body tissues; "fish have simpler hemoglobin than mammals"
(synonym) haemoglobin, Hb
(hypernym) hemoprotein, haemoprotein
(hyponym) oxyhemoglobin, oxyhaemoglobin
(substance-holonym) red blood cell, RBC, erythrocyte
(substance-meronym) heme, haem, hematin, haemitin, protoheme

n. hemoglobin, haemoglobin [Brit.]