noun Cell Biology.
- a large, circulating white blood cell, formed in bone marrow and in the spleen, that ingests large foreign particles and cell debris.
- a large phagocytic leucocyte with a spherical nucleus and clear cytoplasm
- A large, circulating, phagocytic white blood cell that has a single well-defined nucleus and very fine granulation in the cytoplasm and that constitutes from 3 to 8 percent of the white blood cells in humans.
- Any of various large white blood cells that are formed in the bone marrow, circulate in the blood, and destroy pathogenic bacteria by phagocytosis. Monocytes develop into macrophages in various body tissues.