Leukocyte

(LOO-koh-site) A white blood cell. Refers to a blood cell that does not contain hemoglobin. White blood cells include lymphocytes, neutrophils, eosinophils, macrophages, and mast cells. These cells are made by bone marrow and help the body fight infection and other diseases.

White blood cell.

White blood cell, up to 0.02 mm in diameter, of which there are normally 4-11 million per millilitre of human blood. There are several kinds, all involved in the body's defence mechanisms. Granulocytes have granules in their cytoplasm; monocytes ingest and feed on bacteria and other micro-organisms that cause infection; lymphocytes include the B cells that are involved with the production of antibodies.

A white blood cell or corpuscle. Leukocytes are formed from undifferentiated stem cells that give rise to all blood cells.