AU

from WordNet (r) 3.0 (2006)

Au
    n 1: a soft yellow malleable ductile (trivalent and univalent)
         metallic element; occurs mainly as nuggets in rocks and
         alluvial deposits; does not react with most chemicals but
         is attacked by chlorine and aqua regia [syn: {gold}, {Au},
         {atomic number 79}]
    2: a unit of length used for distances within the solar system;
       equal to the mean distance between the Earth and the Sun
       (approximately 93 million miles or 150 million kilometers)
       [syn: {Astronomical Unit}, {AU}]

from The Collaborative International Dictionary of English v.0.48

au \a.u.\ n.
   1. (Astron.) the unit of length equal to the mean distance of
      the Earth from the sun, about 93 million miles (150
      million kiometers); -- used almost exclusively in
      astronomy, or to describe astronomical distances.

   Syn: astronomical unit, AU, A.U.
        [WordNet 1.5]

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

au

   1. <networking> The two character {country code} for Australia
   used in {Internet} {domain names}.

   2. <filename extension> {audio}.

   (1995-02-15)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

AU
       Access Unit