su

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

su

   <operating system, tool, security> (substitute user) The
   {Unix} command which allows you to become another user after
   entering their {password}.  su is most often used without
   arguments in which case it defaults to user {root}.  Some
   versions of Unix only allows this command to be used by
   members of the {wheel} group.

   {Unix manual page}: su(1).

   (1996-09-08)

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

SU
       Screening Units

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

SU
       Selectable Unit

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

SU
       Signalling Unit

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

SU
       Storage Unit

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

SU
       Switch User (Unix)