microcyte

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

• noun An abnormally small red blood cell that is less than five microns in diameter and may occur in certain forms of anemia.

from The Century Dictionary.

• noun A small cell or corpuscle.
• noun A small blood-corpuscle, in size from 2 to 6 micromillimeters, found, often in large numbers, in many cases of anemia.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physiol.) One of the elementary granules found in blood. They are much smaller than an ordinary corpuscle, and are particularly noticeable in disease, as in anæmia.

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

• noun an unusually small red blood cell found in some forms of anemia

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

• noun an abnormally small red blood cell (less than 5 microns in diameter)