corpuscle

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

• noun An unattached body cell, such as a blood or lymph cell.
• noun A rounded globular mass of cells, such as the pressure receptor on certain nerve endings.
• noun A discrete particle, such as a photon or an electron.
• noun A minute globular particle.

from The Century Dictionary.

• noun In electricity, a body smaller than an atom, assumed to explain the phenomena of electric discharges in gases, and of radioactivity.
• noun A minute particle, molecule, or atom of matter.
• noun In zoology and anatomy, some small body regarded by itself and characterized by a qualifying term: usually a body of microscopic size; a cell. See phrases below.
• noun In botany, specifically, one of several large cells within the endosperm and near the summit of the embryo sac in gymnosperms, from which after fertilization an embryo is developed: so named by R. Brown.
• noun Same as corposant.
• noun Of the kidney, small globular masses of dark-red color, found in the cortical substance of the organ, consisting of a central glomerulus of blood-vessels (the Malpighian tuft), and of a membranous capsule which is the beginning of a uriniferous tubule.

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

• noun A minute particle; an atom; a molecule.
• noun (Anat.) A protoplasmic animal cell; esp., such as float free, like blood, lymph, and pus corpuscles; or such as are imbedded in an intercellular matrix, like connective tissue and cartilage corpuscles. See Blood.
• noun (Physics), archaic An electron.
• noun (Physiol.) in man, yellowish, biconcave, circular discs varying from 1/3500 to 1/3200 of an inch in diameter and about 1/12400 of an inch thick. They are composed of a colorless stroma filled in with semifluid hæmoglobin and other matters. In most mammals the red corpuscles are circular, but in the camels, birds, reptiles, and the lower vertebrates generally, they are oval, and sometimes more or less spherical in form. In Amphioxus, and most invertebrates, the blood corpuscles are all white or colorless.
• noun (Physiol.) rounded, slightly flattened, nucleated cells, mainly protoplasmic in composition, and possessed of contractile power. In man, the average size is about 1/2500 of an inch, and they are present in blood in much smaller numbers than the red corpuscles.

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

• noun A minute particle; an atom; a molecule.
• noun A protoplasmic animal cell; esp., such as float free, like blood, lymph, and pus corpuscles; or such as are embedded in an intercellular matrix, like connective tissue and cartilage corpuscles.

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

• noun either of two types of cells (erythrocytes and leukocytes) and sometimes including platelets
• noun (nontechnical usage) a tiny piece of anything