Medical Definition of Neutrophil. Neutrophil: A type of white blood cell, a granulocyte that is filled with microscopic granules, little sacs containing enzymes that digest microorganisms. Also known as polymorphonuclear leukocyte or poly.
Definition of Neutropenia. Neutropenia: Not enough neutrophils, neutrophils being a type of white blood cell (specifically a form of granulocyte) filled with neutrally-staining granules, tiny sacs of enzymes that help the cell to kill and digest microorganisms it has engulfed by phagocytosis.
Neutropenia is an abnormally low number of neutrophils (a type of white blood cell) in the blood. Neutropenia, if severe, significantly increases the risk of life-threatening infection. Neutropenia is often a side effect of the treatment of cancer with chemotherapy or radiation therapy.