Main Entry: leu·ko·blast Variant: or chiefly Britishleu·co·blast/'lü-k&-"blast/noun : a developingleukocyte : a cellular precursor of a leukocyte —compare LYMPHOBLAST, MYELOBLAST
leukoblast leu·ko·blast (l&oomacr;'kə-blāst') n. An immature white blood cell formed during the transition from lymphoidocyte to promyelocyte. Also called proleukocyte.