Thromboembolic refers to the formation of a blood clot (thrombus) that breaks loose and travels through the bloodstream to obstruct a distant vessel. This process is clinically significant because it can cause sudden vascular occlusion, leading to tissue ischaemia or infarction. A common and serious example is pulmonary embolism, where a clot from deep veins blocks pulmonary arteries, posing a life-threatening emergency.