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.
Tread Width Measuring. Tread width is typically thought of as a measurement between the outboard and inboard edges of a new tire's tread design. Ideally it approximates the width of the tread that comes into contact with the road. Unfortunately measuring tire tread width isn't as simple as laying a ruler across the tread.