Hemoglobin is a hemoprotein in blood that helps transport oxygen, and gives blood its red color.
Hemoglobin is the short version of the medical word haemato-globulin, which means something like "blood grains" in Greek. Like many medical terms also derived from the Greek, this one was first used in the 19th century. A doctor doing blood tests might be measuring the levels of hemoglobin in your bloodstream.
