what are eosinophils
Medical Definition of Eosinophil. Eosinophil: A normal type of white blood cell that has coarse granules within its cytoplasm. Eosinophils are produced in the bone marrow and migrate to tissues throughout the body. When a foreign substance enters the body, other types of white blood cells (lymphcytes and neutrophils) release substances to attract eosinophils and then release toxic substances to kill the invader.