red blood cell

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A cell in the blood of vertebrates that transports oxygen and carbon dioxide to and from the tissues. In mammals, the red blood cell is disk-shaped and biconcave, contains hemoglobin, and lacks a nucleus.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun hematology, cytology A type of cell in the blood of vertebrates that contains hemoglobin and transports oxygen from the lungs to the tissues; an erythrocyte.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a mature blood cell that contains hemoglobin to carry oxygen to the bodily tissues; a biconcave disc that has no nucleus