Phlebotomy: Obtaining blood from a vein. In the old days, this was done by incising (cutting) a vein and just letting the blood flow into a container. Today phlebotomy is done more neatly by puncturing a vein with a needle.
Phlebotomy may be done in order to obtain blood for diagnostic tests or to remove blood for treatment purposes (eg, to relieve the iron overload in hemochromatosis).