An obsolete metric unit of distance, defined as 10-12 meter or 10-6micron. This distance is now called a picometer (pm). The name is a reference to the double prefix in "micromicron"
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}