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.
People with neutropenia have an unusually low number of cells called neutrophils. Neutrophils are cells in your immune system that attack bacteria and other organisms when they invade your body. Neutrophils are a type of white blood cell. Your bone marrow creates these cells.