noun.
An abnormally small red blood cell that is less than five microns in diameter and may occur in certain forms of anemia.
The Century Dictionary and Cyclopedia
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.
the GNU version of the Collaborative International Dictionary of English
noun.
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.