A blood clot, also known as a THROMBUS (8 letters), is a clump of blood that has been transformed from a liquid to a solid state. It is formed when certain proteins in the blood interact with each other and form a gel-like substance. Blood clots can form in any part of the body, but are most commonly found in the veins and arteries. They can be dangerous if they block the flow of blood to vital organs, such as the heart or brain.