a unit of distance, usually used to measure the distance to a star, equal to 206,265 astronomical units (3.0857 x 1013 kilometers or 1.92 x 1013 miles or 3.2616 light years): it is the distance at which an angle of 0° 0′ 1″ (one second of arc) would form a triangle having an opposite side with a length of one astronomical unitabbrev. pc
Webster’s New World College Dictionary, Fourth Edition, compiled by the
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