A type of blood cell that is made in the bone marrow and found in the blood. Erythrocytes contain a protein called hemoglobin, which carries oxygen from the lungs to all parts of the body. Also called RBC and red blood cell. (National Cancer Institute, 2024. NCI Dictionary of Cancer Terms. Erythrocyte. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/erythrocyte)