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.
1 Neutropenia is a condition in which the number of neutrophils (a type of white blood cell) in the bloodstream is decreased, affecting the body's ability to fight off infections. 2  Neutropenia is defined as an absolute neutrophil count (ANC) of less than 1500 per microliter (1500/microL).