It comes from the Greek word "erythros" meaning "red."
You'll often see it in medical terms related to blood, such as:
* Erythrocyte: A red blood cell
* Erythropoiesis: The production of red blood cells
* Erythroblast: An immature red blood cell
* Erythema: Redness of the skin
* Erythromelalgia: A condition characterized by burning pain and redness in the extremities