micrometre

from The Free On-line Dictionary of Computing (8 July 2008)

micrometre
micron

   <unit> (Or "micron") One millionth of a {metre}.  The symbol
   is a Greek letter {mu} followed by "m".

   Features on modern {integrated circuits} are typically
   measured in microns.  The smallest features in 1999 are around
   0.1 microns across.

   (1999-09-28)