a mature blood cell that contains hemoglobin to carry oxygen to the bodily tissues; a biconcave disc that has no nucleus
An anucleate hemoglobin-containing cell, especially as found in humans but more generally present in the blood of most vertebrates, that is involved with the transport of oxygen; a red blood cell.
The word erythrocyte comes from combining the Greek roots for "red" and "cell." It refers to red blood cells, named for the red color of their hemoglobin when carrying oxygen.