Thromboembolism is a medical term that refers to the blockage of blood flow in a vessel, usually due to a clot (thrombus) that has broken off and traveled through the bloodstream (embolus). This can occur in various parts of the body, including the deep veins of the legs (deep venous thromboembolism), the arteries supplying the lungs (pulmonary embolism), or other vessels. Thromboembolism is a serious condition that can lead to tissue damage and organ failure if not treated promptly, and may result in long-term complications or even death.