An obstruction causing an embolism: a blood clot, air bubble or other matter carried by the blood stream and causing a blockage or occlusion of a blood vessel
an abnormal particle (such as cholesterol, platelet clump, blood clot, calcium fleck, an air bubble, fat, or some combination of these) circulating in the blood
= tissue particle transported by the blood stream also foreign bodies, a thrombus or gas bubbles, which get stuck when the vessel narrows and thus block the vessel