Pulmonary embolism. Pulmonary embolism Pulmonary embolism occurs when a blood clot gets lodged in an artery in the lung, blocking blood flow to part of the lung. Blood clots most often originate in the legs and travel up through the right side of the heart and into the lungs.
WordReference Random House Unabridged Dictionary of American English Â© 2016. tread (tred), v., trod, trodâ¢den ortrod, treadâ¢ing, n. v.i. 1  to set down the foot or feet in walking; step; walk.  to step, walk, or trample so as to press, crush, or injure something (usually fol. by on or upon):to tread on a person's foot.
Dictionary entry overview: What does treading water mean? â¢ TREADING WATER (noun) The noun TREADING WATER has 1 sense: 1. a stroke that keeps the head above water by thrashing the legs and arms Familiarity information: TREADING WATER used as a noun is very rare.