Neutrophil: 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.
The mature neutrophil has a segmented nucleus (it is called a seg or poly) while the immature neutrophil has band-shape nucleus (it is called a band).
Neutropenia, a decreased proportion of neutrophils, may be seen with viral infections and after radiotherapy and chemotherapy.