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• n  an abnormal particle (e.g. an air bubble or part of a clot) circulating in the blood

• Recently Sir Thomas Lewis, eminent London heart specialist, made a special study of how an arm or leg dies when an embolus (floating clot) plugs a main artery which feeds blood .
• Doctors dread an embolus (from the Greek for a stopper), whether it be a blood clot, a blob of fat, or a bubble of air.
• A thrombus stays in one place; an embolus, which might be a blood clot, or a pocket of air or oil, moves through the blood stream.