Source : Free On-Line Dictionary of Computing

micrometre
     
         (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)