Blood clots

Definition of blood clot
National Cancer Institute

blood clot

(blud klot)
A mass of blood that forms when blood platelets, proteins, and cells stick together. When a blood clot is attached to the wall of a blood vessel, it is called a thrombus. When it moves through the bloodstream and blocks the flow of blood in another part of the body, it is called an embolus.

Source: NCI Dictionary of Cancer Terms